Arch Gynecol Obstet DOI 10.1007/s00404-015-3667-4
MATERNAL-FETAL MEDICINE
Risk factors predicting an emergency cesarean delivery for the second twin after vaginal delivery of the first twin Efrat Spiegel • Roy Kessous • Ruslan Sergienko Eyal Sheiner
•
Received: 20 April 2014 / Accepted: 16 February 2015 Ó Springer-Verlag Berlin Heidelberg 2015
Abstract Objective To investigate obstetrical risk factors predicting failure of vaginal delivery and an emergency cesarean section (CS) for the second twin after vaginal delivery of the first twin. In addition, the study was aimed to define perinatal outcomes of the second twin. Study design A retrospective study was conducted, comparing all deliveries of twins in which CS was performed for the second twin to those in which both twins were delivered vaginally during the years 1988–2010. Women with multiple gestations in which a CS was performed for both twins were excluded from the study. Results During the study period, 1966 vaginal deliveries of the first twin were recorded; 192 involved emergency CS for the second twin. Risk factors for emergency CS of the second twin were preterm delivery, previous CS, placental abruption and breech presentation of the second twin. Perinatal outcomes did not differ between the groups. Conclusion Risk factors for emergency cesarean section of the second twin are preterm delivery, previous CS, placental abruption and breech presentation. Nevertheless,
Abstract presented in part at the SMFM 2013 Annual Meeting, SanFrancisco, USA, Control ID: 1473445. E. Spiegel and R. Kessous are equal contributors. E. Spiegel (&) R. Kessous E. Sheiner Department of Obstetrics and Gynecology, Faculty of Health Sciences, Soroka University Medical Center, Ben-Gurion University of the Negev, POB 151, 84101 Beer-Sheva, Israel e-mail: [email protected] R. Sergienko Epidemiology and Health Services Evaluation, Ben-Gurion University of the Negev, Beer-Sheva, Israel
short-term perinatal outcomes are comparable to twins delivered vaginally. Keywords
Cesarean Section Second twin
Introduction The rate of twin gestation has increased steeply in the past two decades; the incidence of twin pregnancies is currently approximately 3 % of deliveries in the United States [1]. The increase in incidence is related to the advances in technology of assisted reproductive techniques and increase in the proportion of maternities in older women [2]. Unlike singleton pregnancies, twin pregnancies are characterized by a high rate of obstetric complications such as preterm labor and delivery, pre-eclampsia, intra-uterine growth restriction, and other complications increasing perinatal morbidity and mortality [3]. The management of twin pregnancy is the topic for numerous studies, yet many aspects still remain controversial. One of the issues still in dispute is the optimal mode of delivery. The safety of vaginal delivery for twins has long been questioned due to concerns over increased morbidity and mortality of the second twin [4]. Several studies show a dramatic increase in the overall cesarean delivery rate of twin pregnancies over the last 15 years [5, 6]. Nevertheless, under appropriate conditions and with careful patient selection, vaginal twin birth can be associated with minimal neonatal morbidity and a high prospect of success [7]. The increased risk of twin deliveries is mostly associated with the delivery of the second twin. Complications such as cord prolapse, fetal distress, abnormal or unstable lie and placental abruption arise during this infant’s
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delivery [8, 9]. Complications of labor after vaginal delivery of the first twin may necessitate emergent cesarean delivery of the second twin. The cesarean rates for second twins after vaginal delivery of the first twin are quite variable, ranging from 0.33 to 26.8 % [10–12]. Wen et al. studied 61,845 twin births in which the first twins were delivered vaginally. They found the cesarean rate for the second twin to be 9.45 % [11]. Knowledge regarding the factors leading to failure of vaginal delivery and delivery of the second twin by emergency cesarean section may assist clinicians in the management of twin pregnancies. Assessment of the risk posed to the second twin if a cesarean delivery is necessary after the first twin was delivered vaginally, can also shed light on the optimal approach for the management of twin deliveries. The objective of the current study was to investigate obstetrical risk factors predicting failure of vaginal delivery and an emergency cesarean section (CS) for the second twin after vaginal delivery of the first twin. In addition, we aimed to evaluate short-term perinatal outcomes of the second twin.
Materials and methods
follow the obstetrical guidelines that recommend cesarean delivery for extremely premature births with an estimated fetal weight of less than 1500 g. Study design A retrospective population-based study was conducted, comparing all patients who delivered twins with CS performed for the second twin to those in which both twins were delivered vaginally. Women with multiple gestations in which a CS was performed for both twins (like cases of non-vertex first twins) or women lacking prenatal care were excluded from the study. Data regarding pregnancy complications and adverse outcomes were available from the perinatal database of the medical center. Data were reported by an obstetrician immediately after delivery. Skilled medical secretaries routinely reviewed the information prior to entering it into the database. Coding was performed after assessing the medical prenatal care records together with the routine hospital documents. Several demographic and clinical characteristics were evaluated. Different obstetrical risk factors were examined including ante-partum and post-partum complications. The following immediate perinatal outcomes were assessed: Apgar scores at 1 and 5 min \7, birth weight, fetal gender and perinatal mortality.
Setting Statistical analysis The study was conducted at the Soroka University Medical Center, the only hospital in the Negev, the southern region of Israel, serving the entire obstetrical population. Thus, the study represents non-selective population-based data. The Institutional Review Board (in accordance with the Declaration of Helsinki) approved the study. The annual average deliveries during the study period were approximately 12,000–15,000 deliveries. The institute’s Ob–Gyn division consists of 25 delivery rooms, with highly qualified medical staff, day and night, including a senior physician constantly present and two anesthesiologists constantly available in the delivery room. Study population The study population was composed of all patients who delivered twins vaginally with the first twin during 1988–2010. The approach to twin delivery in our institution is to enable vaginal delivery for twins in vertex–vertex and vertex–breech presentations, while non-vertex presentation of the leading twin is an indication for cesarean delivery. Induction of labor in twin pregnancies is indicated for maternal reasons as in singleton pregnancies, and for gestational age, adjusted for twins. Regarding prematurity, we
123
Statistical analysis was performed using the SPSS package 16th edition (SPSS Inc, Chicago, IL, USA). Statistical significance was calculated using the Chi square test for differences in qualitative variables and the Student t test for differences in continuous variables. Odds ratio (OR) and their 95 % confidence intervals (CI) were computed. A value of P \ 0.05 was considered statistically significant.
Results During the study period, 1966 vaginal deliveries of the first twin were recorded out of which 192 involved an emergency CS for the second twin (9.76 %). Table 1 describes the maternal and clinical characteristics of the study subjects. Maternal age, gravidity and ethnicity did not differ statistically between the two study groups. Preterm delivery (\37 weeks of gestation) was found to be a risk factor for cesarean delivery of the second twin. Table 2 compares obstetrical complications according to the mode of delivery. Emergency cesarean delivery rate for the second twin was increased in cases of previous cesarean delivery, placental abruption and in cases of breech presentation of the second twin.
Arch Gynecol Obstet Table 1 Demographic and clinical characteristics of patients Characteristics Maternal age (years ± SD) Ethnicity Gravidity
Vaginal and vaginal (n = 1774)
Vaginal and CS (n = 192)
P value
5.4 ± 29
5.5 ± 29.5
0.310
Jewish
47.9 %
54.2 %
0.019
Bedouin
52.1 %
45.8 %
1
18.7 %
20.3 %
2–4
46.5 %
45.3 %
B5
0.864
0.4.7 %
34.4 %
Preterm delivery \34 weeks
14.6 %
20.3 %
0.034
Preterm delivery \37 weeks
51.6 %
62 %
0.006
51.6 %
62 %
0.020
[37
Gestational age at delivery
37–41
48.2 %
38 %
\42
0.2 %
0%
Table 2 A comparison of pregnancy and delivery complications between patients according to mode of delivery Characteristics
Vaginal and vaginal (n = 1774, %)
Vaginal and CS (n = 192, %)
OR
95 % CI
Mild preeclampsia Severe preeclampsia
5.2 1
1.6 1
0.3 1
0.1–0.9 0.2–4.4
P value 0.026 0.972
Hypertensive disorders
7.9
3.6
0.4
0.2–0.9
0.034
Obesity
0.9
0
0.9
0.88–0.92
0.186
IUGR
1.5
2.1
1.4
0.5–4
0.553
Polyhydramnios
3.4
2.6
0.8
0.3–1.9
0.567
Oligohydramnios
1.2
1.6
1.3
0.4–4.4
0.65
PROM
8.2
9.4
1.1
0.7–1.9
0.586
Gestational Diabetes mellitus
7.7
6.3
0.8
0.4–1.5
0.48
Previous cesarean delivery
3
6.8
2.3
1.2–4.3
0.007
Epidural analgesia
21.8
17.2
0.7
0.5–1.1
0.137
Placenta abruption
1
3.6
3.6
1.5–8.9
0.002
Cord prolapse
0.1
0.5
9.2
0.6–149
0.055
Second twin breech
3.4
11.5
3.6
2.2–6.2
0.001
Post-partum hemorrhage
1.4
1.6
1.1
0.3–3.7
0.865
Blood transfusions Uterine rupture
4.1 0.1
7.8 0
2 0.9
1.1–3.5 0.85–0.95
0.016 0.742
Table 3 presents perinatal and neonatal short-term complications. No statistically significant differences were noted between the two groups in terms of birth weight, Apgar scores and perinatal mortality.
Discussion The main findings of our study were that preterm delivery prior 37 weeks of gestation, previous cesarean delivery, placental abruption and breech presentation of the second twin are major risk factors for emergency cesarean delivery of the second twin after vaginal delivery of the first twin.
Likewise, Wen et al. found that emergent cesarean delivery rate for the second twin was increased in preterm delivery and specifically, between 28 and 35 weeks of gestation [11]. On the contrary, Suzuki et al. found gestational age above 39 weeks to be the most important risk factor of emergent cesarean delivery in the second twin. However, their sample size was smaller and they excluded cases delivered before 33 weeks of gestation [13]. Previous cesarean section was also found as a risk factor for second twin CS. A previous CS by itself, regardless of the indication for the CS, was found to increase the risk for operating on the second twin in the following pregnancy. Varner et al. examined the success rates of trial of labor in
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Arch Gynecol Obstet Table 3 Perinatal and neonatal outcome according to mode of delivery Characteristics
Vaginal and vaginal (n = 1774, %)
Vaginal and CS (n = 192, %)
OR
95 % CI
P value
Male
49.5
54.2
1.2
0.95–1.5
0.084
Female
50.5
45.8
57.9
64.1
1.3
0.9–1.8
0.099
0
0.9
0.88–0.91
0.642
Infant sex
Low birth weight \2500 Macrosomia (birth weight [4 kg)
0.1
Apgar score 1 min \7
8.1
8.3
1
0.6–1.8
0.895
Apgar score 5 min \7
5.5
4.7
0.8
0.4–1.7
0.627
Perinatal mortality (total)
4.7
6.3
1.3
0.7–2.5
0.335
twin pregnancies after at least one previous CS. The authors found no increase in maternal morbidity, yet demonstrated a high rate of women who required CS for the second twin after vaginal delivery of the first twin [14]. In addition, according to the results of our study, placental abruption was found to be a risk factor for cesarean section of the second twin. This result was not adjusted for confounders, such as the time interval between the delivery of the first and second twin. A breech presentation of the second twin was found in 11.5 % of cases of vaginal birth of the first twin and CS for the second twin, in comparison to 3.4 % rate of breech presentation of the second twin, when both were delivered vaginally. Therefore, breech presentation of the second twin is a risk factor for delivery via emergency CS. Our findings correlate with two previous studies in which the non-vertex second twin was associated with a higher risk for cesarean delivery [11, 15]. Importantly, no differences were found considering the immediate perinatal outcomes including low Apgar scores of 1 and 5 min as well as perinatal mortality between the two modes of delivery. It is well known that the Apgar scoring system is a relevant predictor of neonatal survival today as it was in the past [16]. Our findings were consistent with two other studies that found no difference in perinatal morbidity and mortality of the non-vertex twin delivered vaginally or by emergency cesarean section [17, 18]. However, these findings do not correlate with the findings of Wen et al., which demonstrated an increased risk of neonatal mortality in second twins who were delivered by emergency CS after vaginal delivery of the first twin. Yet, it is noted that the increased risk of neonatal death in these cases may not necessarily be related to the procedure itself, but rather to the complications that prevail during the delivery of the second twin, which are difficult to measure and therefore, may lead to residual confounding [19]. Kontopoulos et al. also found higher neonatal mortality rates with vaginal–cesarean deliveries as opposed to CS for both twins as well as vaginal delivery for both twins
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[20]. On the other hand, a recent study assessing neonatal morbidity according to the mode of delivery of the second twin in cephalic/non-cephalic twins, found that neonatal morbidity predictors such as mechanical ventilation, seizure and NICU admission were the same in both delivery modes. Nevertheless, the 5 min Apgar score of the vaginal group was lower than the cesarean group [21]. Our study examined twin deliveries over a 22-year span, which withholds trends in the incidence of preterm birth and in the perinatal morbidity and mortality associated with it. A study published in 2005, reviewed the trends in preterm birth and perinatal mortality for singletons during 1989–2000, and showed an overall mortality rate of 7.8 % for singleton pregnancies of white women in 1989 which declined to 5.4 % by 2000 [22]. Our data is similar to these results, especially when considering that twin pregnancies have higher rates of preterm births and preterm morbidity and mortality. In our data, 62 % of the vaginal–cesarean twin deliveries (n = 192) were preterm deliveries under 37 weeks of gestation, and 20 % of the vaginal-cesarean twin deliveries were under 34 weeks of gestation (which are also included in the \37 weeks group). This means that 42 % of the vaginal–cesarean twin deliveries were between 34 and 37 weeks of gestation. In comparison, 51.6 % of the vaginal–vaginal twin deliveries (n = 1774) were under 37 weeks of gestation and 14.6 % of the vaginal–vaginal twin deliveries were under 34 weeks of gestation, so that 37 % of the vaginal–vaginal twin deliveries were between 34 and 37 weeks of gestation. This reflects the rate of spontaneous twin deliveries under 37 weeks of gestation. The data explains the relatively high rate of perinatal mortality, regardless of the mode of delivery. As for weight differences between the twins, in the assessment of the mode of twin delivery, twin discordance of over 20 % (or selective intra-uterine growth restriction) with the first twin being smaller, may be considered in our institute as an indication for an elective cesarean delivery. When the leading twin is bigger, usually there should be no limitation for vaginal delivery. Therefore, we did not analyze weight
Arch Gynecol Obstet
discrepancy in the risk factors for cesarean delivery of the second twin. The rate of failure for vaginal delivery, and emergency cesarean delivery of the second twin after the first twin was delivered vaginally was 9.76 % in the current study. This rate is similar to the rates found in two other large population studies, which found the risk of failed vaginal delivery of the second twin to be 9.45 % [11], and 10.1 % [23]. A lower rate of 4 % of emergency CS for the second twin was found in a recent cohort of twin deliveries [7], and in two other studies [15, 20], yet these studies had smaller sample sizes. It should be noted that the rate of primary cesarean section in our institution is about 19 %, and remains stable along the years. Our study is a retrospective one, and as such has limitations, mainly that it relies on computerized files. Similarly, using coded data may contain potential errors in the coding and sometimes may lack relevant details. The long time frame of the study may also include changes in obstetric or neonatal practice, which can potentially influence the outcomes. Nevertheless, the data was reported by an obstetrician directly after delivery. Skilled medical secretaries routinely reviewed the information prior to entering it into the database. Coding was done after assessing the medical prenatal care records together with the routine hospital documents. Women lacking prenatal care were excluded from the study analysis. This makes potential source of selection bias less likely. Another limitation of the study is that in similarity to other large population studies, we did not account for twin chorionicity. In conclusion, our study found that risk factors for emergency CS of the second twin are preterm delivery, previous cesarean delivery, placental abruption and breech presentation of the second twin. When assessing and consulting a patient with twin gestation regarding the recommended route of delivery, one should take into consideration these important risk factors. Nevertheless, our results did not demonstrate an increase in the risk for short-term perinatal outcome and found both routes of delivery to be comparable. These results may help in establishing guidelines for the delivery of twin gestation. Conflict of interest of interest.
The authors declare that they have no conflict
Ethical standard The Institutional Review Board in accordance with the Declaration of Helsinki approved the study.
References 1. Martin JA, Kung HC, Mathews TJ, Hoyert DL, Strobino DM, Guyer B, Sutton SR (2008) Annual summary of vital statistics: 2006. Pediatrics 121:788–801
2. Rao A, Shanthi S, Hassan S (2004) Obstetric complications of twin pregnancies. Best Pract Res Clin Obstet Gynaecol 18(4):557 3. Lee YM (2012) Delivery of twins. Semin Perinatol 36(3):195–200 4. Alexander JM, Leveno KJ, Rouse D, Landon MB, Gilbert SA, Spong CY, Varner MW, Caritis SN, Harper M, Wapner RJ, Sorokin Y, Miodovnik M, O’Sullivan MJ, Sibai BM, Langer O, Gabbe SG (2008) Cesarean delivery for the second twin. Obstet Gynecol 112(4):748–752 5. Feldman DM, Borgida AF, Grabo H, Bobrowski RA, Ingardia CJ (2006) Trends in mode of delivery of twins from 1999 to 2004. Obstet Gynecol 107(4):66S–67S 6. Lee HC, Gould JB, Boscardin WJ, El-Sayed YY, Blumenfeld YJ (2011) Trends in cesarean delivery for twin births in the United States: 1995 to 2008. Obstet Gynecol 118(5):1095–1101 7. Breathnach FM, McAuliffe FM, Geary M, Daly S, Higgins JR, Dornan J, Morrison JJ, Burke G, Higgins S, Dicker P, Manning F, Carroll S, Mallone FD (2011) Prediction of safe and successful vaginal twin birth. Am J Obstet Gynecol 205:237.e1–237.e7 8. Williams KP, Galerneau F (2003) Intrapartum influences on cesarean delivery in multiple gestation. Acta Obstet Gynecol Scand 82:241–245 9. Sullivan CA, Harkins D, Seago DP, Roberts WE, Morrison JC (1998) Cesarean delivery for the second twin in the vertex–vertex presentation: operative indications and predictability. South Med J 91:155–158 10. Constantine G, Redman CW (1987) Caesarean delivery of the second twin. Lancet 329(8533):618–619 11. Wen SW, Fung KF, Oppenheimer L, Demissie K, Yang Q, Walker M (2004) Occurrence and predictors of cesarean delivery for the second twin after vaginal delivery of the first twin. Obstet Gynecol 103(3):413–419 12. Olofsson P, Rydhstrom H (1985) Twin delivery: how should the second twin be delivered? Am J Obstet Gynecol 153:479–481 13. Suzuki S (2009) Risk factors for emergency cesarean delivery of the second twin after vaginal delivery of the first twin. J Obstet Gynaecol Res. 35(3):467–471 14. Varner MW, Leindecker S, Spong CY, Moawad AH, Hauth JC, Landon MB, Leveno KJ, Caritis SN, Harper M, Wapner RJ, Sorokin Y, Miodovnik M, Carpenter M, Peaceman A, O’Sullivan MJ, Sibai BM, Langer O, Thorp JM, Ramin SM, Mercer BM, Gabbe SG (2005) The maternal-fetal medicine unit cesarean registry: trial of labor with a twin gestation. Am J Obstet Gynecol 193:135–140 15. Persad VL, Baskett TF, O’Connell CM, Scott HM (2001) Combined vaginal–cesarean delivery of twin pregnancies. Obstet Gynecol 98:1032–1037 16. Casey BM, McIntire DD, Leveno KJ (2001) The continuing value of the apgar score for the assessment of newborn infants. N Engl J Med 344:467–471 17. Adam C, Allen AC, Baskett TF (1991) Twin delivery: influence of the presentation and method of delivery on the second twin. Am J Obstet Gynecol 165:23–27 18. Rabinovici J, Barkai G, Reichman B, Serr DM, Mashiach S (1987) Randomized management of the second nonvertex twin: vaginal delivery or cesarean section. Am J Obstet Gynecol 156:52–56 19. Wen SW, Fung KFK, Oppenheimer L, Demissie K, Yang Q, Walker M (2004) Neonatal mortality in second twin according to cause of death, gestational age, and mode of delivery. Am J Obstet Gynecol 191:778–783 20. Kontopoulos EV, Ananth CV, Smulian JC, Vintzileos AM (2004) The impact of route of delivery and presentation on twin neonatal and infant mortality: a population-based study in the USA, 1995–97. J Matern Fetal Neonatal Med 15(4):219–224
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singletons: United States, 1989 through 2000. Obstet Gynecol 105:1084–1091 23. Ginsberg NA, Levine EM (2005) Delivery of the second twin. Int J Obstet Gynecol 91:217–220
MATERNAL-FETAL MEDICINE
Risk factors predicting an emergency cesarean delivery for the second twin after vaginal delivery of the first twin Efrat Spiegel • Roy Kessous • Ruslan Sergienko Eyal Sheiner
•
Received: 20 April 2014 / Accepted: 16 February 2015 Ó Springer-Verlag Berlin Heidelberg 2015
Abstract Objective To investigate obstetrical risk factors predicting failure of vaginal delivery and an emergency cesarean section (CS) for the second twin after vaginal delivery of the first twin. In addition, the study was aimed to define perinatal outcomes of the second twin. Study design A retrospective study was conducted, comparing all deliveries of twins in which CS was performed for the second twin to those in which both twins were delivered vaginally during the years 1988–2010. Women with multiple gestations in which a CS was performed for both twins were excluded from the study. Results During the study period, 1966 vaginal deliveries of the first twin were recorded; 192 involved emergency CS for the second twin. Risk factors for emergency CS of the second twin were preterm delivery, previous CS, placental abruption and breech presentation of the second twin. Perinatal outcomes did not differ between the groups. Conclusion Risk factors for emergency cesarean section of the second twin are preterm delivery, previous CS, placental abruption and breech presentation. Nevertheless,
Abstract presented in part at the SMFM 2013 Annual Meeting, SanFrancisco, USA, Control ID: 1473445. E. Spiegel and R. Kessous are equal contributors. E. Spiegel (&) R. Kessous E. Sheiner Department of Obstetrics and Gynecology, Faculty of Health Sciences, Soroka University Medical Center, Ben-Gurion University of the Negev, POB 151, 84101 Beer-Sheva, Israel e-mail: [email protected] R. Sergienko Epidemiology and Health Services Evaluation, Ben-Gurion University of the Negev, Beer-Sheva, Israel
short-term perinatal outcomes are comparable to twins delivered vaginally. Keywords
Cesarean Section Second twin
Introduction The rate of twin gestation has increased steeply in the past two decades; the incidence of twin pregnancies is currently approximately 3 % of deliveries in the United States [1]. The increase in incidence is related to the advances in technology of assisted reproductive techniques and increase in the proportion of maternities in older women [2]. Unlike singleton pregnancies, twin pregnancies are characterized by a high rate of obstetric complications such as preterm labor and delivery, pre-eclampsia, intra-uterine growth restriction, and other complications increasing perinatal morbidity and mortality [3]. The management of twin pregnancy is the topic for numerous studies, yet many aspects still remain controversial. One of the issues still in dispute is the optimal mode of delivery. The safety of vaginal delivery for twins has long been questioned due to concerns over increased morbidity and mortality of the second twin [4]. Several studies show a dramatic increase in the overall cesarean delivery rate of twin pregnancies over the last 15 years [5, 6]. Nevertheless, under appropriate conditions and with careful patient selection, vaginal twin birth can be associated with minimal neonatal morbidity and a high prospect of success [7]. The increased risk of twin deliveries is mostly associated with the delivery of the second twin. Complications such as cord prolapse, fetal distress, abnormal or unstable lie and placental abruption arise during this infant’s
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Arch Gynecol Obstet
delivery [8, 9]. Complications of labor after vaginal delivery of the first twin may necessitate emergent cesarean delivery of the second twin. The cesarean rates for second twins after vaginal delivery of the first twin are quite variable, ranging from 0.33 to 26.8 % [10–12]. Wen et al. studied 61,845 twin births in which the first twins were delivered vaginally. They found the cesarean rate for the second twin to be 9.45 % [11]. Knowledge regarding the factors leading to failure of vaginal delivery and delivery of the second twin by emergency cesarean section may assist clinicians in the management of twin pregnancies. Assessment of the risk posed to the second twin if a cesarean delivery is necessary after the first twin was delivered vaginally, can also shed light on the optimal approach for the management of twin deliveries. The objective of the current study was to investigate obstetrical risk factors predicting failure of vaginal delivery and an emergency cesarean section (CS) for the second twin after vaginal delivery of the first twin. In addition, we aimed to evaluate short-term perinatal outcomes of the second twin.
Materials and methods
follow the obstetrical guidelines that recommend cesarean delivery for extremely premature births with an estimated fetal weight of less than 1500 g. Study design A retrospective population-based study was conducted, comparing all patients who delivered twins with CS performed for the second twin to those in which both twins were delivered vaginally. Women with multiple gestations in which a CS was performed for both twins (like cases of non-vertex first twins) or women lacking prenatal care were excluded from the study. Data regarding pregnancy complications and adverse outcomes were available from the perinatal database of the medical center. Data were reported by an obstetrician immediately after delivery. Skilled medical secretaries routinely reviewed the information prior to entering it into the database. Coding was performed after assessing the medical prenatal care records together with the routine hospital documents. Several demographic and clinical characteristics were evaluated. Different obstetrical risk factors were examined including ante-partum and post-partum complications. The following immediate perinatal outcomes were assessed: Apgar scores at 1 and 5 min \7, birth weight, fetal gender and perinatal mortality.
Setting Statistical analysis The study was conducted at the Soroka University Medical Center, the only hospital in the Negev, the southern region of Israel, serving the entire obstetrical population. Thus, the study represents non-selective population-based data. The Institutional Review Board (in accordance with the Declaration of Helsinki) approved the study. The annual average deliveries during the study period were approximately 12,000–15,000 deliveries. The institute’s Ob–Gyn division consists of 25 delivery rooms, with highly qualified medical staff, day and night, including a senior physician constantly present and two anesthesiologists constantly available in the delivery room. Study population The study population was composed of all patients who delivered twins vaginally with the first twin during 1988–2010. The approach to twin delivery in our institution is to enable vaginal delivery for twins in vertex–vertex and vertex–breech presentations, while non-vertex presentation of the leading twin is an indication for cesarean delivery. Induction of labor in twin pregnancies is indicated for maternal reasons as in singleton pregnancies, and for gestational age, adjusted for twins. Regarding prematurity, we
123
Statistical analysis was performed using the SPSS package 16th edition (SPSS Inc, Chicago, IL, USA). Statistical significance was calculated using the Chi square test for differences in qualitative variables and the Student t test for differences in continuous variables. Odds ratio (OR) and their 95 % confidence intervals (CI) were computed. A value of P \ 0.05 was considered statistically significant.
Results During the study period, 1966 vaginal deliveries of the first twin were recorded out of which 192 involved an emergency CS for the second twin (9.76 %). Table 1 describes the maternal and clinical characteristics of the study subjects. Maternal age, gravidity and ethnicity did not differ statistically between the two study groups. Preterm delivery (\37 weeks of gestation) was found to be a risk factor for cesarean delivery of the second twin. Table 2 compares obstetrical complications according to the mode of delivery. Emergency cesarean delivery rate for the second twin was increased in cases of previous cesarean delivery, placental abruption and in cases of breech presentation of the second twin.
Arch Gynecol Obstet Table 1 Demographic and clinical characteristics of patients Characteristics Maternal age (years ± SD) Ethnicity Gravidity
Vaginal and vaginal (n = 1774)
Vaginal and CS (n = 192)
P value
5.4 ± 29
5.5 ± 29.5
0.310
Jewish
47.9 %
54.2 %
0.019
Bedouin
52.1 %
45.8 %
1
18.7 %
20.3 %
2–4
46.5 %
45.3 %
B5
0.864
0.4.7 %
34.4 %
Preterm delivery \34 weeks
14.6 %
20.3 %
0.034
Preterm delivery \37 weeks
51.6 %
62 %
0.006
51.6 %
62 %
0.020
[37
Gestational age at delivery
37–41
48.2 %
38 %
\42
0.2 %
0%
Table 2 A comparison of pregnancy and delivery complications between patients according to mode of delivery Characteristics
Vaginal and vaginal (n = 1774, %)
Vaginal and CS (n = 192, %)
OR
95 % CI
Mild preeclampsia Severe preeclampsia
5.2 1
1.6 1
0.3 1
0.1–0.9 0.2–4.4
P value 0.026 0.972
Hypertensive disorders
7.9
3.6
0.4
0.2–0.9
0.034
Obesity
0.9
0
0.9
0.88–0.92
0.186
IUGR
1.5
2.1
1.4
0.5–4
0.553
Polyhydramnios
3.4
2.6
0.8
0.3–1.9
0.567
Oligohydramnios
1.2
1.6
1.3
0.4–4.4
0.65
PROM
8.2
9.4
1.1
0.7–1.9
0.586
Gestational Diabetes mellitus
7.7
6.3
0.8
0.4–1.5
0.48
Previous cesarean delivery
3
6.8
2.3
1.2–4.3
0.007
Epidural analgesia
21.8
17.2
0.7
0.5–1.1
0.137
Placenta abruption
1
3.6
3.6
1.5–8.9
0.002
Cord prolapse
0.1
0.5
9.2
0.6–149
0.055
Second twin breech
3.4
11.5
3.6
2.2–6.2
0.001
Post-partum hemorrhage
1.4
1.6
1.1
0.3–3.7
0.865
Blood transfusions Uterine rupture
4.1 0.1
7.8 0
2 0.9
1.1–3.5 0.85–0.95
0.016 0.742
Table 3 presents perinatal and neonatal short-term complications. No statistically significant differences were noted between the two groups in terms of birth weight, Apgar scores and perinatal mortality.
Discussion The main findings of our study were that preterm delivery prior 37 weeks of gestation, previous cesarean delivery, placental abruption and breech presentation of the second twin are major risk factors for emergency cesarean delivery of the second twin after vaginal delivery of the first twin.
Likewise, Wen et al. found that emergent cesarean delivery rate for the second twin was increased in preterm delivery and specifically, between 28 and 35 weeks of gestation [11]. On the contrary, Suzuki et al. found gestational age above 39 weeks to be the most important risk factor of emergent cesarean delivery in the second twin. However, their sample size was smaller and they excluded cases delivered before 33 weeks of gestation [13]. Previous cesarean section was also found as a risk factor for second twin CS. A previous CS by itself, regardless of the indication for the CS, was found to increase the risk for operating on the second twin in the following pregnancy. Varner et al. examined the success rates of trial of labor in
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Arch Gynecol Obstet Table 3 Perinatal and neonatal outcome according to mode of delivery Characteristics
Vaginal and vaginal (n = 1774, %)
Vaginal and CS (n = 192, %)
OR
95 % CI
P value
Male
49.5
54.2
1.2
0.95–1.5
0.084
Female
50.5
45.8
57.9
64.1
1.3
0.9–1.8
0.099
0
0.9
0.88–0.91
0.642
Infant sex
Low birth weight \2500 Macrosomia (birth weight [4 kg)
0.1
Apgar score 1 min \7
8.1
8.3
1
0.6–1.8
0.895
Apgar score 5 min \7
5.5
4.7
0.8
0.4–1.7
0.627
Perinatal mortality (total)
4.7
6.3
1.3
0.7–2.5
0.335
twin pregnancies after at least one previous CS. The authors found no increase in maternal morbidity, yet demonstrated a high rate of women who required CS for the second twin after vaginal delivery of the first twin [14]. In addition, according to the results of our study, placental abruption was found to be a risk factor for cesarean section of the second twin. This result was not adjusted for confounders, such as the time interval between the delivery of the first and second twin. A breech presentation of the second twin was found in 11.5 % of cases of vaginal birth of the first twin and CS for the second twin, in comparison to 3.4 % rate of breech presentation of the second twin, when both were delivered vaginally. Therefore, breech presentation of the second twin is a risk factor for delivery via emergency CS. Our findings correlate with two previous studies in which the non-vertex second twin was associated with a higher risk for cesarean delivery [11, 15]. Importantly, no differences were found considering the immediate perinatal outcomes including low Apgar scores of 1 and 5 min as well as perinatal mortality between the two modes of delivery. It is well known that the Apgar scoring system is a relevant predictor of neonatal survival today as it was in the past [16]. Our findings were consistent with two other studies that found no difference in perinatal morbidity and mortality of the non-vertex twin delivered vaginally or by emergency cesarean section [17, 18]. However, these findings do not correlate with the findings of Wen et al., which demonstrated an increased risk of neonatal mortality in second twins who were delivered by emergency CS after vaginal delivery of the first twin. Yet, it is noted that the increased risk of neonatal death in these cases may not necessarily be related to the procedure itself, but rather to the complications that prevail during the delivery of the second twin, which are difficult to measure and therefore, may lead to residual confounding [19]. Kontopoulos et al. also found higher neonatal mortality rates with vaginal–cesarean deliveries as opposed to CS for both twins as well as vaginal delivery for both twins
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[20]. On the other hand, a recent study assessing neonatal morbidity according to the mode of delivery of the second twin in cephalic/non-cephalic twins, found that neonatal morbidity predictors such as mechanical ventilation, seizure and NICU admission were the same in both delivery modes. Nevertheless, the 5 min Apgar score of the vaginal group was lower than the cesarean group [21]. Our study examined twin deliveries over a 22-year span, which withholds trends in the incidence of preterm birth and in the perinatal morbidity and mortality associated with it. A study published in 2005, reviewed the trends in preterm birth and perinatal mortality for singletons during 1989–2000, and showed an overall mortality rate of 7.8 % for singleton pregnancies of white women in 1989 which declined to 5.4 % by 2000 [22]. Our data is similar to these results, especially when considering that twin pregnancies have higher rates of preterm births and preterm morbidity and mortality. In our data, 62 % of the vaginal–cesarean twin deliveries (n = 192) were preterm deliveries under 37 weeks of gestation, and 20 % of the vaginal-cesarean twin deliveries were under 34 weeks of gestation (which are also included in the \37 weeks group). This means that 42 % of the vaginal–cesarean twin deliveries were between 34 and 37 weeks of gestation. In comparison, 51.6 % of the vaginal–vaginal twin deliveries (n = 1774) were under 37 weeks of gestation and 14.6 % of the vaginal–vaginal twin deliveries were under 34 weeks of gestation, so that 37 % of the vaginal–vaginal twin deliveries were between 34 and 37 weeks of gestation. This reflects the rate of spontaneous twin deliveries under 37 weeks of gestation. The data explains the relatively high rate of perinatal mortality, regardless of the mode of delivery. As for weight differences between the twins, in the assessment of the mode of twin delivery, twin discordance of over 20 % (or selective intra-uterine growth restriction) with the first twin being smaller, may be considered in our institute as an indication for an elective cesarean delivery. When the leading twin is bigger, usually there should be no limitation for vaginal delivery. Therefore, we did not analyze weight
Arch Gynecol Obstet
discrepancy in the risk factors for cesarean delivery of the second twin. The rate of failure for vaginal delivery, and emergency cesarean delivery of the second twin after the first twin was delivered vaginally was 9.76 % in the current study. This rate is similar to the rates found in two other large population studies, which found the risk of failed vaginal delivery of the second twin to be 9.45 % [11], and 10.1 % [23]. A lower rate of 4 % of emergency CS for the second twin was found in a recent cohort of twin deliveries [7], and in two other studies [15, 20], yet these studies had smaller sample sizes. It should be noted that the rate of primary cesarean section in our institution is about 19 %, and remains stable along the years. Our study is a retrospective one, and as such has limitations, mainly that it relies on computerized files. Similarly, using coded data may contain potential errors in the coding and sometimes may lack relevant details. The long time frame of the study may also include changes in obstetric or neonatal practice, which can potentially influence the outcomes. Nevertheless, the data was reported by an obstetrician directly after delivery. Skilled medical secretaries routinely reviewed the information prior to entering it into the database. Coding was done after assessing the medical prenatal care records together with the routine hospital documents. Women lacking prenatal care were excluded from the study analysis. This makes potential source of selection bias less likely. Another limitation of the study is that in similarity to other large population studies, we did not account for twin chorionicity. In conclusion, our study found that risk factors for emergency CS of the second twin are preterm delivery, previous cesarean delivery, placental abruption and breech presentation of the second twin. When assessing and consulting a patient with twin gestation regarding the recommended route of delivery, one should take into consideration these important risk factors. Nevertheless, our results did not demonstrate an increase in the risk for short-term perinatal outcome and found both routes of delivery to be comparable. These results may help in establishing guidelines for the delivery of twin gestation. Conflict of interest of interest.
The authors declare that they have no conflict
Ethical standard The Institutional Review Board in accordance with the Declaration of Helsinki approved the study.
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