Accepted Manuscript The Impact of Chorionicity on Maternal Pregnancy Outcomes Ebony B. Carter, MD, MPH, Ms. Katherine C. Bishop, BS, Katherine R. Goetzinger, MD, MSCI, Methodius G. Tuuli, MD, MPH, Alison G. Cahill, MD, MSCI PII:

S0002-9378(15)00503-7

DOI:

10.1016/j.ajog.2015.05.027

Reference:

YMOB 10410

To appear in:

American Journal of Obstetrics and Gynecology

Received Date: 20 January 2015 Revised Date:

27 March 2015

Accepted Date: 13 May 2015

Please cite this article as: Carter EB, Bishop KC, Goetzinger KR, Tuuli MG, Cahill AG, The Impact of Chorionicity on Maternal Pregnancy Outcomes, American Journal of Obstetrics and Gynecology (2015), doi: 10.1016/j.ajog.2015.05.027. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT 1 TITLE: The Impact of Chorionicity on Maternal Pregnancy Outcomes AUTHORS: Ebony B. CARTER, MD, MPH, Ms. Katherine C. BISHOP, BS, Katherine R. GOETZINGER, MD, MSCI, Methodius G. TUULI, MD, MPH, Alison G.

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CAHILL, MD, MSCI

AFFILIATIONS: This study was conducted in St. Louis, Missouri

Washington University School of Medicine, Department of Obstetrics and Gynecology,

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Division of Maternal Fetal Medicine

CONFLICT OF INTEREST/DISCLOSURE STATEMENT: Dr. Carter is supported

interest or financial disclosures. CORRESPONDING AUTHOR: Ebony Boyce Carter, MD, MPH

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by a NIH T32 training grant (5T32HD055172-05). The authors report no conflicts of

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Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine 660 South Euclid Avenue, Maternity Building, 5th Floor, Campus Box 8064 St. Louis, MO 63110; P: (314) 747-1380 F: (314) 747-1429 Email: [email protected]

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Word Count: Abstract: 297 Main text: 2568

Chorionicity and Maternal Outcomes

ACCEPTED MANUSCRIPT 2 CONDENSATION: Maternal outcomes, including incidence of preeclampsia, are similar between monochorionic and dichorionic twin gestations, allowing patients to receive the same

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counseling on maternal risks. SHORT VERSION OF TITAL:

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Chorionicity and maternal outcomes

Chorionicity and Maternal Outcomes

ACCEPTED MANUSCRIPT 3 ABSTRACT Objective: Women carrying twin pregnancies often receive similar counseling, regardless of

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chorionicity, with the notable exception of twin-twin transfusion syndrome (TTTS);

however, little is known about whether the presence of one versus two placentas confers dissimilar maternal risks. We sought to determine differences in maternal and neonatal

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outcomes based on chorionicity. Study Design:

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This was a retrospective cohort study of all twin pregnancies at our institution undergoing routine second trimester ultrasound for anatomic survey from 1990-2010. Secondary outcomes included other adverse maternal and neonatal outcomes. Relative risks (RR) and adjusted odds ratios (aOR) were calculated. Cluster analysis was used to account for

Results:

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non-independence of twin pairs.

Of 2301 pregnancies, 1747 (75.9%) were dichorionic and 554 (24.1%) were

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monochorionic. Rates of preeclampsia, gestational diabetes, placental abruption, placenta previa, preterm labor and preterm premature rupture of membranes (PPROM)

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were not significantly different in dichorionic versus monochorionic pregnancies. Early preterm delivery < 34 weeks (aOR 1.47; 95% CI, 1.17-1.86) and < 28 weeks (aOR 2.58; 95% CI 1.58-4.20) were more likely in monochorionic twins, as was NICU admission (aOR 1.41; 95% CI 1.12-1.78). Monochorionic twins delivered earlier at a mean gestational age of 34.2 weeks versus 35.0 weeks for dichorionic twins (p300 mg in 24 hours or a urine dipstick > 1+ when a 24-hour urine was not available) after 20 weeks of gestation. Other maternal outcomes included gestational diabetes, placental abruption, placenta previa, preterm labor, preterm premature rupture of membranes (PPROM) and cesarean.

Chorionicity and Maternal Outcomes

ACCEPTED MANUSCRIPT 7 Gestational diabetes (GDM) was defined by either clinical criteria (“gestational diabetes” written in the patient chart by a clinical provider) or laboratory criteria (glucose loading test >140 and at least two abnormal values on a 100 gram glucose tolerance test using the

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National Diabetes Group criteria).18 Placental abruption was diagnosed by clinical

criteria (obstetric provider writing “abruption” in medical record at time of delivery), and placenta previa was defined by the placenta covering the cervical os on the last

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ultrasound prior to delivery. Preterm labor was defined as regular contractions resulting in cervical change starting before 37 weeks of gestation, and any patient with clinically

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confirmed rupture of membranes prior to 37 weeks was defined as preterm premature rupture of membranes (PPROM). Perinatal outcomes were small for gestational age (SGA) (birthweight less than the 10th percentile for gestational age), discordance with inter-twin birthweight difference >20%, delivery before 34 and 28 weeks, neonatal

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intensive care unit (NICU) admission, intrauterine fetal demise, neonatal demsie and neonatal length of hospital stay. Infant birthweight was defined by the value listed in the delivery record. Discordance was calculated by taking the difference between

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birthweights and dividing by the birthweight of the larger twin. For the purposes of this study, intrauterine fetal demise was defined as fetal death after the first trimester (14

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weeks gestational age). Neonatal death was defined as death during the first 28 days of life. Length of stay was calculated by subtracting the day of birth from the day of discharge.

A sensitivity analysis excluding pregnancies complicated by monoamnionicity,

twin-twin transfusion syndrome, structural anomalies, or selective reduction was performed.

Chorionicity and Maternal Outcomes

ACCEPTED MANUSCRIPT 8 Data analysis was performed with descriptive and bivariate statistics using unpaired Student’s t-test or Mann-Whitney U test for continuous variables and Chisquare or Fisher exact test for categorical variables as appropriate. We developed

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multivariable logistic regression models to better estimate the impact of chorionicity on maternal and neonatal outcomes while adjusting for potential confounders. Clinically

relevant covariates for inclusion in the initial multivariable statistical models were chosen

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based on biological plausibility and the results of the stratified analyses including

maternal age, African-American race, chronic hypertension, maternal BMI and prior

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preterm birth. These factors were removed in a backward stepwise fashion. Cluster analysis was used to account for non-independence of twin pairs. Final models were tested with the Hosmer-Lemeshow goodness-of-fit test. A p-value of