Journal of Midwifery & Women’s Health

www.jmwh.org

Original Review

An Update on Current Prenatal Testing Options: First Trimester and Noninvasive Prenatal Testing

CEU

Gwen Latendresse, CNM, PhD, Angela Deneris, CNM, PhD

Prenatal genetic testing is rapidly evolving and requires that prenatal care providers stay up-to-date with accurate, evidence-based knowledge. Noninvasive prenatal testing (NIPT), first trimester maternal serum markers, and fetal nuchal translucency are the most recently developed screening tests added to the testing repertoire for detection of chromosomal disorders such as trisomy 21 (Down syndrome). NIPT is a new, highly accurate technique that uses maternal serum and is rapidly being introduced as a first trimester screening tool and increasingly being requested by pregnant women. The American College of Obstetricians and Gynecologists recommends that all pregnant women be offered first and second trimester screening options, regardless of risk status, but does not yet recommend NIPT. It is important for prenatal care providers to be aware of and understand these testing options in order to assist women and their families in making well-informed decisions during pregnancy. The purpose of this article is to update midwives and other prenatal care providers on the current prenatal genetic testing options available and how to appropriately offer and discuss them with their clients. We discuss how these tests work; what to do with the results; and most importantly, how to support and communicate accurate information to women and families as they navigate through an increasingly complicated array of testing choices. c 2015 by the American College of Nurse-Midwives. J Midwifery Womens Health 2015;60:24–36  Keywords: prenatal care, prenatal diagnosis, prenatal genetic testing, prenatal screening

INTRODUCTION

THE BASIS FOR PRENATAL TESTING

Rapid development and implementation of advanced genetics technology in the prenatal setting includes the ability to screen for and diagnose a broader range of diseases and conditions of the fetus at early gestational ages. The fast-paced introduction of newly developed prenatal testing, such as noninvasive prenatal testing (NIPT) of maternal serum in the first trimester, calls for an equally rapid uptake of new knowledge on the part of prenatal care providers. This is particularly true for providers who value and support well-informed decision making that is woman-and family-centered. This article provides an update and discussion of current approaches to prenatal testing options such as ultrasound at 10 to 14 weeks’ gestation for the detection of aneuploidy by measuring the nuchal translucency (NT); maternal serum markers in both the first and second trimester for aneuploidy; and open neural tube defects (ONTDs) and NIPT, which uses cell-free fetal DNA (cff-DNA) circulating in the maternal blood to test for aneuploidy. Issues of test performance and false-positive results are briefly discussed. Testing recommendations and risk assessment are reviewed, and a testing options algorithm is included as a guide for prenatal care providers. Two case presentations illustrate common prenatal testing scenarios. Lastly, we discuss the future horizon of advanced technology and commercialization: directto-consumer (DTC) testing. The glossary found in Table 1 may be helpful for the reader.

It must first be acknowledged that the vast majority of disorders and conditions for which prenatal testing is performed are largely incurable. For example, prenatal testing can screen for and diagnose trisomy 21 (Down syndrome) in a fetus prior to birth, but there is no cure for the condition. However, prenatal testing has many potential benefits for pregnant women, including adequate time to prepare and plan for appropriate health care services; access resources; consider options (including pregnancy termination); engage in psychosocial preparation; and ultimately, to achieve an optimal outcome compatible with the needs, values, and beliefs of each individual woman and her family.1 Modern technology makes it possible to screen for and diagnose conditions prior to birth, such as ONTDs, chromosomal aneuploidies (ie, trisomy 13, 18, 21), congenital defects, and a myriad of single gene inheritable disorders (ie, TaySachs disease, cystic fibrosis, Huntington’s disease, Duchenne muscular dystrophy, hemophilia).1 Although the ability to test for many of these conditions and diseases is not new in prenatal care, advances in technology have significantly changed how and when such tests are performed. The accuracy, ease, and rapid return of results have also improved, particularly during the last 10 to 20 years.2 AN OVERVIEW OF PRENATAL SCREENING AND DIAGNOSTIC TOOLS Screening Versus Diagnostic Tests

Address correspondence to Gwen Latendresse, CNM, PhD, University of Utah College of Nursing, 10 South 2000 East, Salt Lake City, UT 84112. E-mail: [email protected]

It is important to clarify the terms diagnostic and screening in reference to testing for abnormalities. This may seem a small point, but providers and pregnant women and their families frequently get confused about these terms. Screening is

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 c 2015 by the American College of Nurse-Midwives

1526-9523/09/$36.00 doi:10.1111/jmwh.12228

✦ All pregnant women, regardless of risk, should be offered prenatal genetic testing that includes first-trimester maternal serum markers and ultrasound measurement of nuchal translucency, as well as second-trimester maternal serum markers and fetal anatomic ultrasound examination. ✦ Noninvasive prenatal testing uses cell-free fetal DNA in the maternal blood to identify risk for trisomies 21 and 18, and to a lesser extent, trisomy 13. ✦ Chromosomal microarray analysis is recommended for women undergoing chorionic villus sampling or amniocentesis to identify microdeletions and translocations not detected by conventional karyotyping. ✦ Expanded carrier testing is available, regardless of risk status, as an option for identifying hundreds of single gene disorders before or during pregnancy and uses saliva, blood, or skin cells. considered a secondary prevention among healthy individuals, with the goal of early detection of an asymptomatic condition, such as trisomy 21.3 Similar to a Papanicolaou test, screening for fetal aneuploidy simply divides those who may have a condition from those who probably do not. Conversely, diagnostic testing is applied when there is high suspicion that the condition being screened for is actually present (ie, an abnormal screening test), and the goal is to provide a definitive diagnosis.3 Women should be advised that an abnormal screening test is not diagnostic but only an indication of elevated risk. Test Performance: Sensitivity and Specificity, and False-Positive Tests

A good screening test has the ability to detect a condition when it is present, while at the same time have few falsepositive results.3 To evaluate test performance, sensitivity and specificity of the test are the most informative. Sensitivity, also known as detection rate, is the proportion of people with a condition or disease who will also test positive for that condition in a screening test result.3 A highly sensitive test will detect most people with the condition. For example, a sensitivity of 95% means that 95% of those with the disease will also test positive. It also means that 5% of those with the condition will not test positive; thus, the false-negative rate of this test would be 5%. Specificity, in contrast, is the proportion of people without the condition or disease who will also have negative screening test results.3 A specificity of 95% means that 95% of those without the condition will also have a negative test result. This also means that 5% of those without the condition will have a false-positive test result, an aspect of specificity that has generated significant concern and discussion regarding the negative impact of receiving a false-positive test result (ie, worry, stress, and invasive follow-up testing). Lastly, in spite of excellent performance of a particular test, high sensitivity and specificity can be misleading because they are often confused with positive and negative predictive value, which varies depending on prevalence of the condition in a specific population. For example, a first trimester screening for trisomy 21 that includes both maternal serum testing and NT (combined screening) has a sensitivity of 90% and a specificity of 95%, but it still renders a positive predictive value

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(PPV) of only 21.5% in a population for whom the prevalence of trisomy 21 is 1.5% (the reported rate among women at age 40 years). This means that only 21.5% of 40-year-old women with a positive combination test will actually have a fetus with trisomy 21. Conversely, the same population of women with a negative test can be informed that 99.8% of women with a negative test do not have a fetus with trisomy 21. Pregnant women probably are not very interested in the sensitivity and specificity of a test, but they are likely very interested to know what a positive or negative test really means for them. The PPV is the best way to answer the question “what are my chances of having a child with Down syndrome if I have an abnormal screening test?” Although detection and false positive rates are frequently reported, predictive value is not. However, it can easily be calculated and communicated to pregnant women if the sensitivity and specificity of the test are known, as well as the prevalence of the condition in the population screened. An excellent resource for understanding test performance and learning to calculate predictive value can be found in a publication by Fletcher et al.3 A Historical Perspective and the Evolution of Maternal Serum Markers

A higher risk of having a fetus with a chromosomal disorder such as trisomy 21 has long been observed among childbearing women aged 35 years and older, prompting efforts to identify affected fetuses prior to birth for women in this risk category.2 For decades, the option available and recommended to older pregnant women was amniocentesis during the second trimester of pregnancy. Chorionic villus sampling in the first trimester quickly became a second option. Although these tests provide a diagnosis, they are invasive and known to have an associated risk of pregnancy loss. This understandably led to a desire by women and providers alike to find less invasive, lower-risk methods for detecting fetal abnormalities. Subsequently, the use of maternal serum to screen for an increased risk during the second trimester evolved from a single marker (maternal serum alpha fetal protein [MSAFP]) test in the mid-1980s, to a multiple biochemical markers serum testing approach (eg, triple or quad screen) that detects risk for aneuploidy and ONTDs.2 Given the low-risk, noninvasive profile of maternal multiple-marker serum testing, it

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Table 1. Glossary of Terms

Term Aneuploidy

Definition A chromosomal condition in which there is an abnormal number of chromosomes in the complement of 23 pairs by either deletion or addition of a chromosome. Common aneuploidies include trisomy 13, 18, and 21.

Cell-free fetal DNA (cffDNA)

Fetal genetic material (DNA) not contained within cells and which circulates freely in the blood of a pregnant woman is thought to comprise 3%-13% of the total cell-free DNA in maternal blood. Derived primarily from the placenta, it can currently be used to test for aneuploidy in high-risk women (ie, noninvasive prenatal testing).

Chromosomal microarray analysis (CMA)

A technique for identifying chromosomal abnormalities, including those that are too small (ie, microdeletions) to be detected by conventional karyotyping. Requires direct testing of fetal tissue, thus can only be offered when chorionic villus sampling or amniocentesis is performed.

Chromosomal microdeletions

These are very small deletions of a part of a chromosome or sequence of DNA and result in a loss of genetic material. They usually are not fatal, but frequently result in physical and mental abnormalities, depending on the genetic material that is lost. Conventional karyotyping is not able to identify microdeletions. Cri du chat is a syndrome caused by a microdeletion on the short arm of chromosome 5.

Chromosomal translocation

A rearrangement of chromosomal parts between different chromosomes. These can be balanced (even exchange of material) or unbalanced (unequal exchange of material resulting in extra or missing genetic material). Although there is frequently no effect on phenotype, individuals with chromosomal translocations may have an increased risk of nonviable conception and trisomy 21. Balanced translocations may require chromosomal microarray analysis for identification, but unbalanced translocations might be identifiable by conventional karyotyping.

Karyotype

An individual’s full complement of chromosomes. Also used to refer to the visual display of an individual’s chromosomes, arranged in a standardized format (ie, in chromosomal pairs).

Noninvasive prenatal testing (NIPT)

A blood sample collected from a pregnant woman contains cell-free fetal genetic material (DNA). Available technology offers a highly sensitive assay for using the sample to detect aneuploidy, specifically trisomy 21 and 18, and to some extent, trisomy 13.

Phenotype

The outward expression or the observable traits of a person, usually resulting from some

Trisomy

A chromosomal condition in which 3 chromosomes occur where there should only be a pair.

combination of genotype and environmental influences. The occurrence increases in neonates born to older mothers. A common trisomy condition is trisomy 21 (Down syndrome).

quickly became a routine prenatal screening option over the last 2 decades and is now offered to low-risk women younger than 35 years, as well as to those women who have a higher a priori risk. In the last 7 to 10 years, newer first-trimester testing options that include ultrasound measurement of NT and maternal serum markers have rapidly become available; sufficient evidence indicates equivalent or superior performance of screening with these tests during the first trimester compared to second trimester maternal-serum screening.4,5 In 2007, the American College of Obstetricians and Gynecologists (ACOG) issued a recommendation that all women, regardless of risk status, be offered both first and second trimester prenatal screening options.2

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Using maternal serum is an effective, relatively noninvasive method for identifying fetal risk, particularly for aneuploidy and ONTDs.2 Biochemicals produced by the placenta are present in the maternal circulation and offer a convenient proxy (marker) for identifying risk in the fetus. These multiple markers include pregnancy associated protein (PAPP-A), human chorionic gonadotropin (hCG), alpha fetoprotein (AFP), estradiol (uE3), and inhibin A (DIA). The normal values of these biochemical markers vary depending on gestational age and maternal characteristics such as age, race/ethnicity, weight, presence of diabetes, or singleton versus multiple gestation.6 Accurate test interpretation and risk determination are therefore dependent on accurate pregnancy dating and reporting of relevant maternal

Volume 60, No. 1, January/February 2015

characteristics. Indeed, this is why the first order of business for abnormal test results is to confirm pregnancy dating and reporting of maternal factors relevant to test accuracy. The most recently developed technology introduces the ability to use cell-free fetal (cff)- DNA, which freely circulates in the maternal blood, to test for chromosomal abnormalities, genetic abnormalities, and fetal sex. The cff-DNA is continually being released into maternal circulation from placental trophoblastic cells undergoing normal apoptosis.7 One test currently available, NIPT, is designed to detect aneuploidy, specifically trisomies 21, 18, and 13, as early as 10 weeks’ gestation by measuring proportionally additional chromosome cff-DNA from the fetus.8,9 Ultrasonography

Ultrasonography has long been used to noninvasively establish fetal well-being and identify morphologic abnormalities. Advances in ultrasound technology provide increasingly high-definition images and the ability to associate anatomic findings with a risk for aneuploidy and a variety of congenital disorders in the fetus.10 For example, phenotypic characteristics often found in individuals with trisomy 21 include nuchal thickening, shortened limbs, hyperechoic bowel, and hypoplastic nose.10 Ultrasound examination in the first trimester can identify nuchal thickening, and anatomical ultrasound in the second trimester is effective in identifying dysmorphology.5,6 FIRST TRIMESTER SCREENING OPTIONS

There are several screening options currently available to women in the first trimester of pregnancy for the detection of aneuploidy.5,6 These tests include use of maternal serum or fetal measurement by ultrasound examination, alone or in combination. First trimester screening allows more time for pregnant women and their significant others to process test results and to make important decisions earlier in the pregnancy when compared to second trimester screening. First trimester screening is only for the detection of aneuploidy; thus, if testing for ONTDs is desired, a maternal serum AFP level will need to be obtained and evaluated at 15 to 22 weeks’ gestation.2 Nuchal Translucency in the First Trimester

First trimester screening options include ultrasound examination for the detection of aneuploidy by measurement of the fetal NT, often referred to as nuchal fold. Screening is best conducted between 10 and 14 weeks’ gestation, and maternal serum markers are commonly added and referred to as combined screening in the first trimester. If the NT measurement cannot be adequately measured by transabdominal ultrasound, then a transvaginal ultrasound should be performed. The generally accepted thickness of the nuchal fold is less than 3 mm for a euploid fetus. Nuchal folds that measure more than 3 mm indicate a greater risk of aneuploidy because the NT is thicker in aneuploid fetuses.11 Additionally, the increased NT has been associated with heart, brain, urinary system, and abdominal anomalies—as well as other Journal of Midwifery & Women’s Health r www.jmwh.org

major anomalies.12 Ultrasound during the first trimester is limited to NT evaluation and cannot adequately evaluate fetal anatomy given the early stage of fetal development. Therefore, for a complete anatomical survey of the fetus, an ultrasound during the second trimester is also necessary for the detection of other morphologic abnormalities.12 Maternal Serum Markers in the First Trimester

First trimester maternal serum markers for the detection of aneuploidy include PAPP-A and hCG.5 Marker levels are reported as a multiple of the median (MoM), which is derived from dividing an individual’s serum concentration by the population mean for the specific gestational age. By definition, the median level is 1.0 MoM, and a test result of 3.4 MoM, for example, would mean 340% of the median. Likewise, a test result of 0.4 MoM would mean 40% of the median. This is a quantifiable method for estimating risk based on whether a specific woman’s concentrations of hCG or PAPP-A are lower or higher than expected for the gestational age. Increased hCG above the 95th percentile and decreased PAPP-A below the fifth percentile are associated with a higher risk of trisomies 21, 18, and 13.13,14 Noninvasive Prenatal Testing

NIPT utilizing cff-DNA in maternal blood was initially reported in 199715 and was first used to determine fetal gender and Rhesus blood antigen status. NIPT technology has rapidly developed due to the desire for a more reliable, noninvasive method of screening and diagnosis for chromosomal disorders. Clinically available since 2011, NIPT is a highly sensitive screening test in high-risk women such as those with advanced maternal age, positive serum screening markers, and fetal structural anomalies found on ultrasound. For the detection of trisomy 21 and trisomy 18, NIPT has a greater than 99% detection rate and less than 0.1% false-positive rate. The sensitivity is less for trisomy 13, for which it has an approximately 80% detection rate and a 1% false-positive rate.16 Some NIPT tests also have the ability to identify X or Y chromosome disorders, such as Turner and Klinefelter syndromes, fetal rhesus D determination, and some single gene disorders.17 The accuracy of the NIPT is dependent on the proportion of cff-DNA to maternal DNA in the maternal plasma and currently must be at least 4%. Optimal NIPT testing occurs when the test is performed at 10 to 12 weeks’ gestation or more at which time the cff-DNA has reached approximately 10% of the maternal DNA.16 NIPT is less sensitive in women who are obese or who are of Afro-Caribbean descent.16 Therefore, NIPT should be offered no earlier than 12 weeks’ gestation for these women. Lastly, NIPT is not currently recommended for women with multiple gestation.18,19 The sensitivity (99%) and specificity (99.8%) of NIPT is substantially better than the sensitivity and specificity of maternal serum markers (80% and 95%, respectively).20 Although test performance nearly matches that for diagnostic tests (for aneuploidy), women with positive NIPT results are referred for chorionic villi sampling or amniocentesis to confirm the findings. This is due to the inability of NIPT to detect 50% of chromosomal abnormalities, such as 27

unbalanced translocations, microdeletions, duplications, maternal or placental mosaicism, and single-gene mutations.17,18 NIPT is also not a screening test for ONTDs, so maternal serum AFP screening should be offered between 15 to 20 weeks’ gestation for ONTDs screening. Because cff-DNA is cleared quickly from maternal blood, usually by 72 hours, a positive result in a previous pregnancy will not confound test results in the next pregnancy.21 There currently are 4 private industry companies in the United States offering NIPT, with costs ranging from $795 to $2762 for each test. Health insurance companies are beginning to cover the cost of NIPT for ACOG-recommended indications (ie, advanced maternal age). Although NIPT is more expensive, a cost analysis of NIPT versus first trimester serum markers suggests that NIPT reduced the number of unnecessary invasive procedures by more than 95%. In addition, it also reduced the incidence of invasive testing-associated pregnancy loss among normal fetuses by more than 99%22 due to a false-positive rate of less than 0.1% for NIPT16 compared to the false-positive rate of 5% for first trimester and integrated screening.2 Aside from the cost, NIPT may spare women and their families from unnecessary anxiety associated with false-positive test results and subsequent invasive procedures that are more common with other first and second trimester screening tests. NIPT may eventually be approved as an option that is routinely offered to all pregnant women, regardless of risk status. Indeed, some predict that NIPT has the potential to revolutionize genetic fetal testing. Development is already underway for whole-genome or targeted DNA sequencing and other genetic tests for couples desiring genetic information about their fetus.23,24 SECOND TRIMESTER SCREENING OPTIONS

Second trimester screening options such as maternal serum markers (MSAFP, triple, quad) and ultrasound examination have been the mainstay of prenatal testing for decades and are commonly accepted as routine components of prenatal care in developed countries.13 The vast majority of prenatal care providers are fully knowledgeable about these screening tests, and many are comfortable ordering these tests for pregnant women. Fetal Anatomical Ultrasound in the Second Trimester

Ultrasound examination is more successful at evaluating fetal anatomy after approximately 18 weeks’ gestation and aims to evaluate morphology, as well as identify anomalies and any physical characteristics associated with specific disorders. During a standard second or third trimester ultrasound (sometimes referred to as a level II ultrasound), sonographers conduct a detailed anatomic examination of multiple fetal structures, including the spine, cranium and ventricles, heart and chambers, stomach, bowel, kidneys, upper and lower extremities, face, umbilical cord, and diaphragm.10 To maximize the ability to detect fetal abnormalities, the American Institute of Ultrasound in Medicine recommends that all standard ultrasounds are performed by a highly trained sonographer— and, in addition to a thorough fetal anatomic examination, 28

they should document fetal presentation, amniotic fluid volume, cardiac activity, placental location, and fetal biometry.25 The examination becomes more complex and lengthy if the need for finer detail is identified. Maternal Serum Markers in the Second Trimester

To identify risk for ONTDs and chromosomal/genetic disorders in the second trimester, maternal blood can be collected and used to measure serum levels of chemical markers, optimally between 15 to 18 weeks’ gestation.13 The test is often referred to as the quad screen due to the use of 4 serum markers: AFP, hCG, uE3, and inhibin A. Serum levels are reported in MoM based on normal levels for the woman’s gestational age and characteristics such as race/ethnicity, weight, or presence of diabetes. Elevated AFP levels are associated with an increased risk of ONTDs. Abnormally low levels of uE3 and AFP, and abnormally high levels of hCG and DIA, are all associated with an increased risk for chromosomal abnormalities, particularly trisomy 21.13 INTEGRATED AND SEQUENTIAL SCREENING OPTIONS

All of the screening options described thus far can be combined in ways that can provide more patient participation in testing decisions and/or the ability to increase the detection rate of specific disorders. Integrated screening combines both first and second trimester screening of maternal serum markers and ultrasound examinations and provides a risk score based on results from all the tests together.6,26 The risk score is not calculated until all tests from both trimesters have been completed. In contrast, sequential testing calculates a risk score for each set of screening tests from each trimester.6,26 This allows risk to be communicated to the pregnant woman during the first trimester and allows time to determine whether she would like to continue with second trimester screening tests and/or opt for diagnostic testing after input from a genetic counselor and/or prenatal care provider. DIAGNOSTIC TESTING OPTIONS Amniocentesis, Chorionic Villus Sampling, and Chromosomal Microarray Analysis

Chorionic villus sampling in the first trimester and amniocentesis in the second trimester are still the gold standard diagnostic tests for the definitive identification of aneuploidies via karyotyping.20 Furthermore, DNA sequencing for single gene disorders such as cystic fibrosis and hemophilia— and chromosomal microarray analysis (CMA), which identifies submicroscopic chromosomal abnormalities—are currently performed in many centers nationally.27 CMA examines fetal DNA via microarray or gene chip technology, which compares hundreds of known DNA locations from the 46 chromosomes, thus identifying submicroscopic abnormalities. Disorders that cannot be identified by traditional karyotyping, such as chromosomal microdeletions and translocations, can be identified with CMA.28 CMA is most beneficial when inconsistent fetal dysmorphology is noted on ultrasound or if a neonate is born with congenital anomalies, Volume 60, No. 1, January/February 2015

dysmorphic features, neurocognitive disabilities, and/or autism spectrum disorders.29 Because these invasive tests have a small but concerning risk of pregnancy loss and infection, noninvasive diagnostic tests, that is, noninvasive prenatal diagnosis (NIPD), are in rapid development and forecasted to replace amniocentesis and chorionic villus sampling in the future.19 NIPD, similar to NIPT, uses maternal serum to isolate and analyze fetal DNA in order to diagnose multiple disorders such as single gene disorders and chromosomal aberrations, in addition to trisomies. Expanded Carrier Testing: Parental or Preconception Testing

Parental or, ideally, preconception genetic testing for recessive single gene and chromosomal disorders is always an option, whereby cells/DNA are taken noninvasively by collection of saliva, blood, or skin cells directly from individuals.1 This approach offers the ability for both DNA sequencing for the diagnosis of autosomal recessive disorder carrier status and chromosomal structural analyses to diagnose heritable chromosomal disorders among prospective parents. Although these are diagnostic tests for parents or prospective parents, they provide a means for genetic risk screening for the fetus. Parental single gene carrier screening for severe recessive disorders with a higher prevalence in specific populations, such as Tay-Sach disease, beta thalassemia, and sickle cell anemia, has been routinely available to expectant and prospective couples for several decades. However, the most recent trend is the availability of expanded carrier testing to all women and couples, regardless of risk status, particularly prior to pregnancy.30 The basic expanded carrier tests can detect approximately 100 recessive inheritable disorders, including several variants of cystic fibrosis. The more extensive tests are advertised to identify several hundred genetic mutations with varying degrees of health consequence. Genetic counseling pre- and postexpanded carrier testing is still strongly recommended because a positive result of the expanded carrier testing can be confusing and anxiety-producing. Couples need to understand that they would both have to be carriers of the same recessive genetic disease to potentially have a fetus with the disorder. There are several companies currently providing expanded carrier testing. The cost of the test ranges from $99 to $1,000, and most insurance companies are not currently covering this test. Preimplantation Genetic Diagnosis

Preconception testing for carrier status leads to the question of what to do when both prospective parents are identified as carriers of a severe recessive disorder, such as Tay-Sach disease or cystic fibrosis. Unfortunately, many parents discover their carrier status after their newborn has been diagnosed with a severe recessive condition, therefore prompting decision making for any future pregnancies. Some options include the choice not to procreate; choosing to become pregnant, thus taking the 25% chance of having a fetus with a recessive disorder; choosing to terminate versus continue a pregnancy if the fetus does have the disorder; and use of a donor egg or sperm from a noncarrier. Journal of Midwifery & Women’s Health r www.jmwh.org

A recently available option is preimplantation genetic diagnosis of an embryo from parents with known genetic disease or carrier status and the willingness (and financial means) to use assisted reproductive technology, in vitro fertilization, embryo testing, and subsequent transfer of a disease-free embryo.31,32 Obviously, preimplantation genetic diagnosis is available primarily in developed countries and is usually highly regulated due to societal concerns, particularly regarding the eugenic implications. However, for many prospective parents who want to avoid the heartache and devastation of having a newborn with a severe or fatal genetic disease/disorder, preimplantation genetic diagnosis can be viewed as a blessing. Disorders that are autosomal recessive and autosomal dominant and sex-linked, as well as chromosomal and single-gene disorders, can be identified using preimplantation genetic diagnosis.32 Cystic fibrosis, beta-thalassemia, sickle cell disease, myotonic dystrophy, Huntington’s disease, fragile X syndrome, hemophilia A, and Duchenne muscular dystrophy are the conditions for which preimplantation genetic diagnosis is most commonly performed.31 TEST AVAILABILITY AND PERFORMANCE

Table 2 provides a summary of all screening and diagnostic tests currently available and the appropriate timing for each test.33 However, it is best to identify what is available at your institution and laboratory because availability of these tests may vary widely. Furthermore, what is current as of the publication date for this article will likely change, sometimes seemingly overnight. An important aspect of any type of testing is the ability of the test to accurately detect a condition, as well as the number of false-positives that occur. A test with low sensitivity (detection rate) will render more false-negative results and therefore false reassurance. Conversely, a test that has low specificity will render more false-positive results (false alarms), which often creates unnecessary worry for women and their families.1 Table 3 provides the detection and false-positive rates for currently available tests.33 WHICH TEST, WHEN, AND FOR WHOM?

Risk assessment is an important first step toward appropriate counseling and the selection of screening and diagnostic testing. Advanced maternal age is a commonly known risk factor for chromosomal aneuploidies and is a clinical prompt for offering screening and/or diagnostic testing to pregnant women, including first trimester NIPT and ultrasound examination. However, there are several red flags that should alert prenatal care providers to the increased risk for chromosomal and genetic disorders and congenital malformations (see Table 4).34 The conduct of a thorough personal and family medical and genetic history will assist in risk identification, and there are reputable resources available for assessing risk including online forms and downloadable software.35,36 Options, Choices, and Recommendations

Figure 1 provides a clinical algorithm that may be useful to prenatal care providers as they counsel women about prenatal screening and diagnostic options. The algorithm is based 29

Table 2. Prenatal Screening and Diagnostic Tests Currently Available

Testing Available for These Conditions Recommended Gestational Age for Testing

Test

Aneuploidy

ONTD

Genetic

Congenital

Mutation

Anomalies

First trimester screening 10-14 weeks

Ultrasound: NT measurement

x

10-14 weeks

Maternal Serum: PAPP-A and hCG

x

10+ weeks

NIPT (maternal serum)

x

CVS for karyotyping, CMA, and/or direct DNA

x

x

First trimester diagnostics 10-14 weeks

x

testing Second trimester screening 15-23 weeks (optimal 18)

Ultrasound: Anatomic examination

x

x

x

15-18 weeks

Maternal serum: multiple marker (quad): AFP,

x

x

x

x

x

x

x

x

hCG, uE3, and inhibin A Integrated Screening

Combines first and second trimester screening as a comprehensive risk assessment

Sequential

First trimester screening, followed by second trimester, as indicated by first trimester test results

Anytime

NIPT (maternal serum)

x

Amniocentesis for karyotype, CMA and/or

x

Second trimester diagnostics 15-22 weeks

x

x

direct DNA testing, plus amniotic fluid AFP level Anytime diagnostics: Prepregnancy, parents, newborn, embryo Anytime from parents prior to or during pregnancy, or in

Direct DNA and chromosomal testing using

x

x

x

x

blood, saliva, or skin cells

the newborn or siblings During assisted reproduction, PGD of embryo ie, in vitro fertilization Abbreviations: AFP, alpha fetoprotein; CMA, chromosomal microarray analysis; CVS, chorionic villus sampling; hCG, human chorionic gonadotropin; NIPT, noninvasive prenatal testing; NT, nuchal translucency (thickness); ONTDs, neural tube defect; PAPP-A, pregnancy associated plasma protein A; PGD, preimplantation genetic diagnosis; uE3, unconjugated estriol. Adapted with permission from Varney’s Midwifery, 5th edition.33

predominantly on ACOG level A recommendations (good and consistent scientific evidence).2 ACOG and the National Society of Genetic Counselors make several statements and recommendations regarding prenatal testing, which can be found in Table 5.4,18,29 Genetic Counseling

Referral to a genetic counselor can be helpful for women with identified risk factors or positive screening test results. For example, women of advanced maternal age, hereditary disorder or hereditary disorder carrier status, abnormal maternal serum marker testing results, or abnormal ultrasound examination would be candidates for genetic counseling referral.19 In many settings, women are routinely referred for genetic counseling when any risk factors have been identified 30

and prior to initiating first trimester screening or diagnostic testing. Genetic counselors are knowledgeable professionals who assist individuals and families to understand genetic risk, screening and diagnostic testing options, coordinate testing, interpret results, and provide follow-up and referral to other health professionals, as needed.4 Together with the prenatal care provider, they can be instrumental in assisting women and families to navigate the very difficult psychosocial terrain of an impactful diagnosis and to clarify personal values and beliefs. However, genetic counselors often are not available in many health care settings, particularly outside urban areas and tertiary care facilities.37 Consequently, many prenatal care providers play a significant role in providing genetic counseling. Volume 60, No. 1, January/February 2015

Table 3. Detection and False-Positive Rates for Currently Available Prenatal Testsa

Test

Detection Rate,b %

False-Positive Rate,c %

68 (trisomy 21)

5 (trisomy 21)

68 (trisomy 18)

0.5 (trisomy 18)

First trimester screening NT measurement alone

72 (trisomy 13) Maternal serum markers alone

67 (trisomy 21)

5 (trisomy 21)

80 (trisomy 18)

0.5 (trisomy18 and 13)

59 (trisomy 13) Combined NT measurement and maternal serum markers

90 (trisomy 21)

5 (trisomy 21)

97 (trisomy 18)

0.5 (trisomy 18 and 13)

84 (trisomy 13) Second trimester screening Maternal serum markers alone

80 (trisomy 21)

5 (trisomy 21)

(quad)

70 (trisomy 18)

0.2 (trisomy 18 and 13)

19 (trisomy 13)

2–5 (ONTDs)

75–90 (ONTDs) 95 (anencephaly) Anatomic US alone

Maternal quad and US

73 (trisomy 21)

4 (trisomy 21)

93–100 (trisomy 18)

4 (trisomy 18)

90–100 (trisomy 13)

0.5 (trisomy 13)

83 (trisomy 21)

5 (trisomy 21)

100 (trisomy 18)

0.4 (trisomy 18)

100 (trisomy 13)

0.5 (trisomy 13)

Integrated/sequential screening First and second trimester

86 (trisomy 21)

2 (trisomy 21)

maternal serum without NT

86 (trisomy 18)

0.5 (trisomy 18 and 13)

49 (trisomy 13) First and second trimester maternal serum with NT

95 (trisomy 21)

4 (trisomy 21)

92 (trisomy 18)

0.5 (trisomy 18 and 13)

72 (trisomy 13) Chorionic villus sampling (CVS)

98 (Aneuploidy)

⬍ 0.04

Amniocentesis

99.5 (Aneuploidy)

⬍ 0.04

96–99 (ONTDs)

2 (ONTDs)

Noninvasive Prenatal Testing

99 (trisomy 21 and 18)

0.3 to 1 (overall)

Direct DNA testing:

99.9

92 (trisomy 13) ⬍ 0.04

Saliva, blood, placental, or skin cell sample for identification of genetic mutation and carrier status Abbreviations: NT, nuchal translucency (thickness); ONTDs, open neural tube defects; US, ultrasound. a Detection and false-positive rates can vary depending on population risk and risk cutoff used in testing. b Detection rate reflects test sensitivity (accuracy or ability of test to correctly identify those who have a disorder). c False-positive rate reflects test specificity (ability of test to correctly identify those who do not have a disorder). Adapted with permission from Varney’s Midwifery, 5th edition, Erratum. Available at: http://www.jblearning.com/catalog/9781284025415/.

Journal of Midwifery & Women’s Health r www.jmwh.org

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Table 4. Genetic Red Flags

Advanced maternal age (aged 35 years or older) High-risk ethnic/racial heritage (ie, Ashkenazi Jewish, Mediterranean, African American) Consanguinity (blood relationship of parents) Family history (mother’s and father’s) of a known or suspected genetic condition Multiple affected family members with the same or related disorders Any major malformations (ie, heart, kidney, brain) or other birth defects occurring in mother, father, grandparents, offspring, or close relatives (brothers/sisters) Congenital blindness or deafness in family members Extremely tall or short stature of mother, father, or their relatives Developmental delays or mental retardation occurring in mother, father, offspring, or close relatives Recurrent pregnancy losses (2 or more) for the mother Environmental exposure to known or suspected teratogens Infertility or premature ovarian failure Adapted with permission from National Coalition of Health Professional Education in Genetics34 ; March of Dimes.35

Risk Status

Test Results

Available Options st

Low Risk b Women

c

1 Trimester Screening: Maternal Serum Markers Sonogram for NT

Final Disposition Available Options

Test Results −

nd

−

2 Trimester Screening: Maternal Serum Markers Fetal anatomic sonogram

+

NIPT

−

Diagnostic Testing: CVS or Amniocentesis Karyotype vs. CMA

+

+

Referral to Genetics Counselor

st

c

1 Trimester Screening: Maternal Serum Markers Sonogram for NT High Risk b Women

NIPT

− +

−

nd

2 Trimester Screening: Maternal Serum Markers Fetal anatomic sonogram

+ −

c

Diagnostic Testing: CVS or amniocentesis Karyotype vs. CMA

+

Anticipate newborn without aneuploidy or identifiable genetic or d congenital defect Anticipate newborn with an accurately identified chromosomal, genetic or congenital defect

Anticipate newborn without aneuploidy or identifiable genetic or d congenital defect Anticipate newborn with an accurately identified chromosomal, genetic or congenital defect

Referral to Genetics Counselor

Figure 1. Algorithm for Offering Prenatal Testing Optionsa Abbreviations: CMA, chromosomal microarray analysis; CVS, chorionic villus sampling; NIPT, noninvasive prenatal testing; NT, nuchal translucency/thicknes; ONTDs, open neural tube defect a Based predominantly on level A recommendations (good and consistent scientific evidence). Source: ACOG5 b Women are considered high risk when specific risk factors apply (see Table 4), that is, women who will be 35 years of age and older at expected due date, have a personal or family history of congenital malformations (especially major) or known genetic or chromosomal disorders, and higher risk ethnic/racial background. In the absence of risk factors, women are considered low risk. c First trimester screening for aneuploidy will not detect risk for ONTDs. If a woman does not have second trimester screening or amniocentesis, she should be informed that ONTDs-specific screening is available (ie, second trimester ultrasound alone or in combination with maternal serum alpha serum protein). d Negative screening tests are not a 100% guarantee that a fetus is without aneuploidy or ONTDs, and diagnostic testing has limitations (ie, does not detect all possible genetic or congenital abnormalities).

CASE PRESENTATIONS

First Case Presentation

Two cases are presented to assist the reader in making practical application of prenatal testing knowledge to the clinical setting.

Mary is a 29-year-old Gravida 3, Para 2 who has had 2 fullterm healthy pregnancies. Mary and her partner were offered routine prenatal testing, including first and second trimester

32

Volume 60, No. 1, January/February 2015

ultrasound and maternal serum screening. They chose to have second trimester maternal serum testing (quad) and ultrasound examination. The quad test was abnormal, indicating a risk of 1 out of 98 for trisomy 21. The ultrasound examination was entirely normal. After assurance that the correct information had been provided to the lab for accurate calculation of risk (ie, ultrasound confirmation of correct gestational age, ethnicity, maternal weight, and age) the midwife communicated the results to Mary. Available options were discussed, including NIPT; diagnostic amniocentesis; and a second, more complex anatomic ultrasound examination. Mary wanted to discuss the results with her partner and stated that she would let the midwife know what she wanted to do, if anything. Mary did not call back with a decision prior to her next prenatal appointment. Mary and her partner came to the next prenatal visit at 28 weeks’ gestation, declining any further testing because any additional results “would not change our plans” for the pregnancy. She also felt reassured that the fetus was fine because the routine ultrasound found nothing obvious. She declined a referral for a visit with the genetic counselor. At 37 1/7 weeks’ gestation, Mary had a normal, spontaneous vaginal birth of a viable newborn with a nonvigorous cry, poor color, and Apgar scores of 6 and 8. Bilateral single palmar creases were noted, as well as other features compatible with trisomy 21. Genetic testing confirmed the diagnosis of Down syndrome. Second Case Presentation

Margit is a 38-year-old Gravida 1, Para 0. She presented for her first prenatal visit at 10 1/7 weeks’ gestation, at which time the midwife discussed available prenatal testing options with Margit and her partner. Given her age, Margit was offered a referral to a genetics counselor, which was accepted. Margit was also scheduled for a first trimester ultrasound for the following day. The ultrasound findings indicated a gestational age of 9.6 weeks and a “nuchal area slightly prominent, although it is too early to measure.” Margit had an appointment with the genetic counselor at 13 2/7 weeks’ gestation and the couple chose to have NIPT completed on the same day. NIPT results were provided one week later at 14 3/7 weeks’ gestation and were positive for “increased representation of chromosome 18 material.” Margit was contacted by telephone by the genetic counselor; after discussion with her husband, she decided to proceed with an amniocentesis. This was scheduled for the following week, at 15 4/7 weeks’ gestation. On the day of the amniocentesis, Margit had a preprocedure sonogram that revealed multiple fetal anomalies, including abnormal head shape with a Chiari 2 malformation of the brain, lumbosacral myelomeningocele, upper limb defects, clubbing of the hands, and early growth restriction. These findings were discussed with Margit and her partner prior to the amniocentesis procedure. Given the sonogram and NIPT results, the couple declined the recommended amniocentesis and chose to go home to further discuss and consider the situation and their options. The midwife contacted the couple by telephone to answer any further questions they might have and to provide emotional and decision-making support. Given the very poor prognosis, Margit and her partner made a decision to terminate the pregnancy the following week. Journal of Midwifery & Women’s Health r www.jmwh.org

Communicating With Women and Families

These 2 case presentations provide real examples of the importance of communicating with women and families about their options in prenatal testing. Unless prenatal care providers adequately and clearly inform women about prenatal testing, they can feel overloaded with information and confused by options or that they had not received sufficient information. Table 6 lists specific topics and information currently recommended by ACOG and the National Society of Genetic Counselors.2,4 However, the most effective way to relay information has not been established and may depend on an individual’s cultural and educational background and unique learning style and abilities.38 Furthermore, within the context of a busy prenatal clinic setting, prenatal care providers may not have adequate time to sufficiently discuss available options. One common approach is to provide printed information about prenatal testing during the first or second prenatal visit, accompanied with direction to “read the information and let us know what you would like to do.” This approach fails to recognize the increasingly complex information being provided and the potential difficulty in understanding what it means. In at least one study, only 50% of providers actually discussed prenatal testing at all; and among those who did, an average of one minute was spent in discussion of the topic.39 This situation can significantly impact the ability of women to make well-informed decisions about prenatal testing. The March of Dimes and the National Coalition of Health Professional Education in Genetics offer some solutions that may be more effective education and decision-making approaches, including culturally appropriate online, video, and software formats.35,36 Lastly, it is important to keep in mind that women and families, even providers, may confuse the difference between screening and diagnostic tests, concluding that a fetus has Down syndrome when they are informed of an abnormal quad screen, for example. Furthermore, the financial and emotional ramifications of false-positive test results can have considerable negative impact. Women and their families should be made aware of the possibility of false-positive test results and what these findings really mean (Table 6).

Ethical Issues in Prenatal Testing

It is beyond the scope of this article to comprehensively discuss the financial, ethical, and societal issues involved in prenatal and genetic testing. However, it is important to acknowledge that health care providers, ethicists, researchers, and policy makers around the globe are grappling with the financial, ethical, legal, and societal implications of advancements in genetics technology. The National Human Genome Research Institute, established in 1990, funds and manages a wide variety of research, workshops, consortia, and policy conferences specifically geared to ward addressing the financial, ethical, legal, and societal implications.40 FUTURE HORIZONS Direct to Consumer Movement

Direct-to-consumer (DTC) testing is a controversial and rapidly growing industry. Companies advertise genetic-based 33

Table 5. ACOG and NSGC Recommendations for Prenatal Testing

First and second trimester screening (ultrasound and maternal serum markers) should be routinely offered to all women regardless of risk status or age. NIPT should be offered only to women with specific high risk factors: Maternal age ࣙ 35 years, ultrasound findings suspicious for aneuploidy, history of previous pregnancy affected by trisomy, abnormal maternal serum test results, and parental balanced Robertsonian translocation with increased risk of trisomy 13 or 21. NIPT should be an informed patient choice after pretest counseling and should not be a part of routine prenatal laboratory assessment. This is based on the fact that NIPT has not been sufficiently evaluated in low-risk women (or in multiple gestations). Invasive prenatal diagnosis (CVS or amniocentesis) and referral to genetics counseling is recommended for all women with positive NIPT results, especially prior to making any irreversible pregnancy management decisions (ie, pregnancy termination). Chromosomal microarray analysis (CMA) should be offered instead of standard karyotyping to women who have a fetus with a structural abnormality found on ultrasound and have chosen to proceed with CVS or amniocentesis. CMA should be offered to all women who are undergoing amniocentesis or CVS (for any reason), and to women with a fetal demise or stillbirth. ACOG does not currently recommend CMA for pregnancy loss during the first and second trimesters Abbreviations: ACOG, American College of Obstetricians and Gynecologists; CMA, chromosomal microarray analysis; CVS, chorionic villus sampling; NIPT, noninvasive prenatal testing; NSGC, National Society of Genetic Counselors. a Based predominantly on level A recommendations (good and consistent scientific evidence). Source: ACOG18,29 ; NSGC.4

Table 6. Informing Women About Prenatal Testing Options

At a minimum, pregnant women should be informed of: The conditions for which they can be screened Method of screening Likelihood of detection Meaning of positive and negative test results Meaning of false-positive and negative test results Choices following positive screening Choices following positive diagnosis How additional information can be gathered Source: ACOG2 ; NSGC.4

testing directly to consumers by Internet, television, and other marketing approaches. These companies have operated under very little government oversight and sometimes provide access to testing without the involvement of a knowledgeable health care provider. Some DTC companies have boardcertified genetic counselors to review their test results and answer patient and provider questions. Many require consumers to have a health care provider place the order and receive the results. Testing to determine ancestry, ethnicity, paternity, and even gender are popular with consumers and are easily available from many companies. For consumers who are curious about disease risk and hereditary conditions, including pregnant women concerned about risk to offspring, some companies offer DTC testing with costs ranging from $99 to $1,200 per test, some of which may be reimbursed by insurance. Some companies have broad claims of determining more than 300 conditions and hereditary traits, and this number is expected to increase. One significant argument for DTC testing is the ability for any prospective parent to test for hereditary conditions, such as, Tay-Sach’s disease in the Jewish community, and to address the issue before pregnancy and without stigma and discrimination.41 34

Proponents of DTC testing cite consumer autonomy, empowerment, and enhanced privacy—and perhaps lower testing costs.42 At the same time, there is much concern about usefulness, reliability, and potential for harm from DTC testing.43 For example, the US Food and Drug Administration (FDA) warns that consumers may receive test results that are inaccurate and thus may subsequently make serious and consequential health decisions based on those results.44 The American College of Medical Genetics issued a policy statement in 2008 advising that “a knowledgeable professional should be involved in the process of ordering and interpreting a genetic test” and stating that “the consumer should be fully informed regarding what the test can and cannot say about his or her health. The scientific evidence on which a test is based should be clearly stated.”45 Misunderstanding test results could have grave consequences and cause unnecessary concern or false reassurances among consumers. On November 22, 2013, amid these concerns about test reliability, the FDA issued its first warning ever to a DTC company, directing them to discontinue marketing and sales of genetic tests until evidence of validated studies could be provided.46 The International Society of Genetic Genealogy has a list of genomic companies offering DTC testing.47 Becaue DTC is likely here to stay, adequate consumer education must be addressed and is essential for consumers to appropriately select DTC tests, receive accurate test results and interpretations, and follow any recommended health actions based on those results.43 CONCLUSION

The field of prenatal testing is rapidly expanding with new and future possibilities arising seemingly overnight. Prenatal care providers must be well informed about current recommendations for screening and diagnostic testing, as well as risk assessment, in order to continue to provide evidence-based, contemporary care to the women and families that they serve. Furthermore, prenatal care providers must be prepared to respond knowledgeably and appropriately to the inquiries and Volume 60, No. 1, January/February 2015

requests put before them by clients. It is probably safe to state that the genomics era is here to stay, and it will continue to advance. Although it is true that many genetic conditions cannot currently be cured, it certainly can be argued that screening for genetic conditions and diagnosing them can improve the outcomes for those affected. AUTHORS

Gwen Latendresse, CNM, PhD, FACNM, is Assistant Professor at the University of Utah College of Nursing, where she teaches, conducts research, and provides midwifery care. Angela Deneris, CNM, PhD, FACNM, is Professor (clinical) at the University of Utah College of Nursing, where she teaches and provides midwifery care. CONFLICT OF INTEREST

The authors have no conflicts of interest to disclose. REFERENCES 1.Norton ME. Genetic screening and counseling. Curr Opin Obstet Gynecol. 2008;20(2):157-163. 2.ACOG Practice Bulletin No. 77: screening for fetal chromosomal abnormalities. Obstet Gynecol. 2007;109(1):217-227. 3.Fletcher R, Fletcher S, Fletcher G. Clinical Epidemiology: The Essentials. 5th ed. Baltimore, MD: Lippincott Williams & Wilkins; 2014. 4.Wilson KL, Czerwinski JL, Hoskovec JM, et al. NSGC practice guideline: Prenatal screening and diagnostic testing options for chromosome aneuploidy. J Genet Couns. 2013;22(1):4-15. 5.Driscoll DA, Gross SJ. First trimester diagnosis and screening for fetal aneuploidy. Genet Med. 2008;10(1):73-75. 6.Chitayat D, Langlois S, Wilson RD. Prenatal screening for fetal aneuploidy in singleton pregnancies. J Obstet Gynaecol Can . 2011;33(7):736-750. 7.Tjoa ML, Cindrova-Davies T, Spasic-Boskovic O, Bianchi DW, Burton GJ. Trophoblastic oxidative stress and the release of cell-free feto-placental DNA. Am J Pathol. 2006;169(2):400-404. 8.Bianchi DW, Platt LD, Goldberg JD, et al. Genome-wide fetal aneuploidy detection by maternal plasma DNA sequencing. Obstet Gynecol. 2012;119(5):890-901. 9.Swanson A, Sehnert AJ, Bhatt S. Non-invasive prenatal testing: technologies, clinical assays and implementation strategies for women’s healthcare practitioners. Curr Genet Med Rep. 2013;1(2):113-121. 10.Gagnon A, Wilson RD, Allen VM, et al. Evaluation of prenatally diagnosed structural congenital anomalies. J Obstet Gynaecol Can. 2009;31(9):875-881, 882-879. 11.Kagan KO, Avgidou K, Molina FS, Gajewska K, Nicolaides KH. Relation between increased fetal nuchal translucency thickness and chromosomal defects. Obstet Gynecol. 2006;107(1):6-10. 12.Goldstein I, Weizman B, Nizar K, Weiner Z. The nuchal translucency examination leading to early diagnosis of structural fetal anomalies. Early Hum Dev. 2014;90(2):87-91. 13.Alldred S, Deeks J, Guo B, Neilson J, Alfirevic Z. Second trimester serum tests for Down’s syndrome screening. Cochrane Database Syst Rev. 2012;(6):CD009925. 14.Karadzov-Orlic N, Egic A, Filimonovic D, et al. Screening for aneuploidies by maternal age, fetal nuchal translucency and maternal serum biochemistry at 11-13+6 gestational weeks. Srp Arh Celok Lek. 2012;140(9-10):606-611. 15.Lo YM, Corbetta N, Chamberlain PF, et al. Presence of fetal DNA in maternal plasma and serum. Lancet. 1997;350(9076):485-487. 16.Ashoor G, Syngelaki A, Poon LC, Rezende JC, Nicolaides KH. Fetal fraction in maternal plasma cell-free DNA at 11–13 weeks’ gestation:

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Relation to maternal and fetal characteristics. Ultrasound Obstet Gynecol. 2013;41(1):26-32. 17.Daley R, Hill M, Chitty LS. Non-invasive prenatal diagnosis: Progress and potential. Arch Dis Child Fetal Neonatal Ed. 2014. DOI: 10.1136/archdischild-2013-304828. 18.American College of Obstetricians and Gynecologists Committee on Genetics. Committee Opinion No. 545: non-invasive prenatal testing for fetal aneuploidy. Obstet Gynecol. 2012;120(6):1532-1534. 19.Devers PL, Cronister A, Ormond KE, Facio F, Brasington CK, Flodman P. Noninvasive prenatal testing/noninvasive prenatal diagnosis: the position of the National Society of Genetic Counselors. J Genet Couns. 2013;22(3):291-295. 20.National Coalition for Health Professional Education in Genetics. Non-invasive prenatal testing (NIPT) factsheet. 2012; http://www. nchpeg.org/index.php?option = com content&view = article&id = 384&Itemid = 255. Accessed June 17,-2014. 21.Hui L, Vaughan JI, Nelson M. Effect of labor on postpartum clearance of cell-free fetal DNA from the maternal circulation. Prenat Diagn. 2008;28(4):304-308. 22.Song K, Musci TJ, Caughey AB. Clinical utility and cost of non-invasive prenatal testing with cfDNA analysis in high-risk women based on a US population. J Matern Fetal Neonatal Med. 2013;26(12):1180-1185. 23.Hudecova I, Sahota D, Heung MM, et al. Maternal plasma fetal DNA fractions in pregnancies with low and high risks for fetal chromosomal aneuploidies. PLoS One. 2014;9(2):e88484. 24.Benn P, Cuckle H, Pergament E. Non-invasive prenatal testing for aneuploidy: current status and future prospects. Ultrasound Obstet Gynecol. 2013;42(1):15-33. 25.American Institute of Ultrasound in Medicine. AIUM practice guideline for the performance of obstetric ultrasound examinations. J Ultrasound Med. 2013;32(6):1083-1101. 26.Cocciolone R, Brameld K, O’Leary P, Haan E, Muller P, Shand K. Combining first and second trimester markers for Down syndrome screening: Think twice. Aust N Z J Obstet Gynaecol. 2008;48(5):492500. 27.Pergament E, Pergament D. Reproductive decisions after fetal genetic counselling. Best Pract Res Clin Obstet Gynaecol. 2012;26(5):517529. 28.Wapner RJ, Driscoll DA, Simpson JL. Integration of microarray technology into prenatal diagnosis: Counselling issues generated during the NICHD clinical trial. Prenat Diagn. 2012;32(4):396-400. 29.American College of Obstetricians and Gynecologists Committee on Genetics. Committee opinion on no. 581: the use of chromosomal microarray analysis in prenatal diagnosis. Obstet Gynecol. 2013;122(6):1374-1377. 30.Benn P, Chapman AR, Erickson K, et al. Obstetricians’ and gynecologists’ practice and opinions of expanded carrier testing and noninvasive prenatal testing. Prenat Diagn. 2013;34(2):145-152. 31.Audibert F, Wilson RD, Allen V, et al. Preimplantation genetic testing. J Obstet Gynaecol Can. 2009;31(8):761-775. 32.Vendrell X, Bautista-Llacer R. A methodological overview on molecular preimplantation genetic diagnosis and screening: A genomic future? Syst Biol Reprod Med. 2012;58(6):289300. 33.Latendresse G. Genetics. In Brucker M, King T, eds. Varney’s Midwifery. 5th ed. Burlington, MA: Jones & Bartlett Learning; 2013. 34.National Coalition for Health Professional Education in Genetics. Risk Assessment. Pregnancy & health profile 2014; http://www.nchpeg. org/index.php?option = com content&view = article&id = 411& Itemid = 278. Accessed June 17, 2014, 2014. 35.National Coalition for Health Professional Education in Genetics. The pregnancy & health profile: A risk assessment & screening tool. 2014; http://www.nchpeg.org/index.php?option = com content&view = article&id = 410&Itemid = 277. Accessed June 17, 2014. 36.March of Dimes. Family health history form. 2014; http://www. marchofdimes.com/glue/files/family-health-history-form.pdf. Accessed June 17, 2014.

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44.Valles SA. Should direct-to-consumer personalized genomic medicine remain unregulated?: A rebuttal of the defenses. Perspect Biol Med. 2012;55(2):250-265. 45.American College of Medicine Genetics Board of Directors ACMG Statement on Direct-to-Consumer Genetic Testing. Rockville, MD: American College of Medical Genetics; 2008. 46.Clarke T, Begley S. FDA warns Google-backed 23andMe to halt sales of genetic tests. Reuters. November 25, 2013, 2013. 47.International Society of Genetic Genealogy. List of DNA Testing Companies. http://www.isogg.org/wiki/List of DNA testing˙companies. Accessed June 17, 2014.

Continuing education units (CEUs) for this article are offered as part of a CEU theme issue. To obtain CEUs online, please visit www.jmwhce.org. A CEU form that can be mailed or faxed is available in the print edition of the theme issue.

Volume 60, No. 1, January/February 2015