Optimal timing of labor induction after prelabor rupture of membranes at term: a secondary analysis of the TERMPROM study.

BACKGROUND: In the case of prelabor rupture of membranes at term, the risk for neonatal and maternal infectious morbidity increases progressively with time from prelabor rupture of membranes. Although most studies identified a benefit associated with early induction within the first 24 hours following term prelabor rupture of membranes, there is currently no precise data regarding how early should induction be scheduled. OBJECTIVE: This study aimed to identify the optimal timing of labor induction among women with term prelabor rupture of membranes by comparing the maternal and neonatal outcomes associated with labor induction with those of expectant management at any given 1-hour interval following prelabor rupture of membranes. STUDY DESIGN: This was a secondary analysis of data from the TERMPROM trial, an international, multicenter, randomized clinical trial on immediate delivery vs expectant management of women with prelaor rupture of membranes at term (≥37+0/7 weeks' gestation). We considered all participants as a single cohort of women with term prelabor rupture of membranes, irrespective of the original randomized study group allocation. For each given 1-hour time interval within the first 36 hours following prelabor rupture of membranes, we compared the outcomes of subjects for whom labor induction was initiated during this interval with those of subjects managed expectantly at the same time interval. The primary neonatal outcome was a composite of neonatal infection and admission to the neonatal intensive care unit. The primary maternal outcomes included maternal infection (clinical chorioamnionitis or postpartum fever) and cesarean delivery. RESULTS: Of the 4742 subjects who met the study criteria, 2622 underwent labor induction, and 2120 experienced a spontaneous onset of labor. The rates of the neonatal composite outcome, neonatal admission to intensive care unit, and maternal infection increased progressively with time after prelabor rupture of membranes. The risk for these outcomes was lower among women who underwent induction when compared with those managed expectantly within the first 15 to 20 hours after prelabor rupture of membranes without affecting the risk for cesarean delivery. In addition, women who underwent labor induction within the first 30 to 36 hours had a shorter prelabor rupture of membranes to delivery time and a shorter total maternal hospital stay when compared with those managed expectantly at the same time interval. Among women managed expectantly, less than two-thirds (64%; 1365/2120) experienced a spontaneous onset of labor within the first 24 hours following prelabor rupture of membranes. CONCLUSION: These findings suggest that immediate labor induction seems to be the optimal management strategy to minimize neonatal and maternal morbidity in the setting of prelabor rupture of membranes at term gestations. In cases for which immediate induction is not feasible, labor induction remains the preferred option over expectant management if performed within the first 15 to 20 hours after prelabor rupture of membranes.

Maternal weight gain and pregnancy outcomes in twin gestations.

BACKGROUND: Data on the optimal gestational weight gain in twin pregnancies are limited. As a result, the Institute of Medicine currently provides only provisional recommendations on gestational weight gain in this population. OBJECTIVE: This study aimed to identify the optimal range of gestational weight gain in twin pregnancies and to estimate the association between inappropriate gestational weight gain and adverse pregnancy outcomes. STUDY DESIGN: This was a retrospective cohort study of all women with twin pregnancies that were followed up in a single, tertiary center between 2000 and 2014. We used 2 approaches to identify the optimal range of gestational weight gain: a statistical approach (the interquartile range of gestational weight gain in low-risk pregnancies with normal outcomes) and an outcome-based approach (by identifying thresholds of gestational weight gain below or above which the rate of adverse outcomes increases). The primary outcome was preterm birth. Associations of gestational weight gain below or above the normal range with the study outcomes were estimated using logistic regression analysis and were expressed as adjusted odds ratio with 95% confidence intervals. These associations were stratified by prepregnancy body mass index group. RESULTS: A total of 1274 women with twin pregnancies met the study criteria: 43 were classified as underweight, 777 were normal weight, 278 were overweight, and 176 were obese. Our estimates of the optimal gestational weight gain range were similar to those recommended by the Institute of Medicine except for the obese category, in which our optimal gestational weight gain range at 37 weeks (9.3-16.3 kg) was lower than in the provisional Institute of Medicine recommendations (11.3-19.1 kg). Nearly half of our cohort experienced inappropriate gestational weight gain: 30% (n=381) gained weight below and 17% (n=216) gained weight above current Institute of Medicine recommendations. In the normal weight group, gestational weight gain below recommendations was associated with an increased risk of preterm birth and birthweight at the <10th centile and with a reduction in the risk of hypertensive disorders, whereas gestational weight gain above recommendations was associated with an increased risk of hypertensive disorders and a reduction in the risk of birthweight at the <10th centile. Associations were less consistent in the overweight and obese groups. CONCLUSION: These findings identify gestational weight gain as a potentially modifiable risk factor for preterm birth and other pregnancy complications in twin gestations. Further prospective studies are needed to determine whether interventions aimed at optimizing gestational weight gain can improve the outcomes of these high-risk pregnancies.

Current Practice of Maternal-Fetal Medicine Specialists Regarding the Prevention and Management of Preterm Birth in Twin Gestations.

OBJECTIVE: To investigate the current practices of maternal-fetal medicine (MFM) specialists regarding the prevention and management of preterm birth (PTB) in twin pregnancies. METHODS: This was a cross-sectional study of Canadian MFM specialists. Participants responded to an anonymous survey regarding the prevention and management of PTB in twins, including lifestyle and gestational weight gain recommendations, cervical length screening, PTB prevention, and labour and delivery practices. RESULTS: Of 137 MFM specialists surveyed, 95 (69%) responded. Most MFM specialists recommend against activity restriction (77.9%), avoidance of sexual activity (96.7%), routine progesterone (97.8%), routine prophylactic cerclage (98.9%), and routine administration of antenatal corticosteroids (95.6%). There were considerable inconsistencies with respect to gestational weight gain management. Despite lack of support by guidelines, most MFM specialists reported using routine cervical length screening (97.8%) and progesterone for short cervix (92.3%). Over half (52.7%) of MFM specialists recommend cervical cerclage when the cervix is <15mm. In cases of PTB, most MFM specialists recommend vaginal delivery when twins are in vertex presentation (63%-75%). MFM specialists are less likely to recommend vaginal delivery when twin B is non-vertex (35%-41%). CONCLUSION: There is a considerable variation among MFM specialists regarding the prevention and management of PTB in twins, and the practice of many MFM specialists differs from that recommended by professional societies' guidelines. These findings underscore the necessity for high-quality studies and up-to-date recommendations.

Identification of the optimal growth chart and threshold for the prediction of antepartum stillbirth.

PURPOSE: To evaluate the effect of the choice growth chart and threshold used to define small for gestational age (SGA) on the predictive value of SGA for placenta-related or unexplained antepartum stillbirth. METHODS: A retrospective cohort study of all women with a singleton pregnancy who gave birth > 24 week gestation in a single center (2000-2016). The exposure of interest was SGA, defined as birth weight < 10th or < 25th centile according to three fetal growth charts (Hadlock et al., Radiology 181:129-133, 1991; intergrowth-21st (IG21), WHO 2017, and a Canadian birthweight-based reference-Kramer et al., Pediatrics 108:E35, 2001). The outcome of interest was antepartum stillbirth due to placental dysfunction or unknown etiology. Cases of stillbirth attributed to other specific etiologies were excluded. RESULTS: A total of 49,458 women were included in the cohort. There were 103 (0.21%) cases of stillbirth due to placental dysfunction or unknown etiology. For cases in the early stillbirth cluster (≤ 30 weeks), the detection rate was high and was similar for the three ultrasound-based fetal growth charts of Hadlock, IG21, and WHO (range 83.3-87.0%). In contrast, the detection rate of SGA for cases in the late stillbirth cluster (> 30 weeks) was low, being highest for WHO and Hadlock (36.7% and 34.7%, respectively), and lowest for IG21 (18.4%). Using a threshold of the 25th centile increased the detection rate for stillbirth by approximately 15-20% compared with that achieved by the 10th centile cutoff. CONCLUSION: At > 30 week gestation, the Hadlock or WHO fetal growth charts provided the best balance between detection rate and false positive rate for stillbirth.

The relationship between maternal body mass index and pregnancy outcomes in twin compared with singleton pregnancies.

OBJECIVE: Women with twins have an a priori increased risk for many of the complications associated with maternal obesity. Thus, the impact of maternal obesity in twins may differ from that reported in singletons. In addition, given the increased metabolic demands in twin pregnancies, the impact of maternal underweight may be greater in twin compared with singleton gestations. Our objective was to test the hypothesis that the relationship between maternal pre-pregnancy body mass index (BMI) and adverse pregnancy outcomes differ between twin and singleton gestations. METHODS: This was a retrospective population-based study of all women who had a singleton or twin hospital birth in Ontario, Canada, between April 2012 and March 2016. Data were obtained from the Better Outcomes Registry & Network (BORN) Ontario. The relationship between maternal BMI category and pregnancy complications was assessed separately in twin and singleton gestations. The primary outcome was a composite variable that included any of the following complications: preeclampsia, gestational diabetes, or preterm birth before 320/7 weeks. Relative risk (aRR) and 95% confidence intervals (CI) for adverse outcomes for each BMI category as defined by WHO (using normal weight category as reference) were generated using modified Poisson regression, adjusting for maternal age, nulliparity, smoking, previous preterm birth, and fetal sex. RESULTS: A total of 487,870 women with singleton (n = 480,010) and twin (n = 7860) pregnancies met the inclusion criteria. The risk of the composite primary outcome, preeclampsia, gestational diabetes, and cesarean delivery increased with high maternal BMI in both singleton and twin gestations, but these associations were weaker in twin compared with singleton gestations (association of BMI ≥ 40.0 kg/m2 with primary outcome: aRR = 3.10, 95%-CI 2.96-3.24 in singletons compared with aRR = 1.74, 95%-CI 1.37-2.20 in twins). In singleton pregnancies the risk of preterm birth at < 320/7 weeks increased with maternal BMI, mainly due to an increased risk of provider-initiated preterm birth. In twin gestations, however, underweight (but not overweight or obesity) was associated with the greatest risk of preterm birth at < 32 weeks (aRR 1.67, 95%-CI 1.17-2.37), mainly due to an increased risk of spontaneous preterm birth (aRR 2.10, 95%-CI 1.44-3.08). CONCLUSION: In healthy women with twin pregnancies, underweight is associated with the greatest risk for preterm birth, while the association of maternal obesity with adverse pregnancy outcomes is weaker than that observed in singletons.

Delivery of monochorionic twins: lessons learned from the Twin Birth Study.

BACKGROUND: The current literature regarding the recommended mode of delivery of monochorionic-diamniotic twins is limited to small numbers, retrospective studies, and comparisons of outcomes of monochorionic-diamniotic twin pregnancies with those of dichorionic-diamniotic twin pregnancies instead of outcomes of trial of labor vs elective cesarean delivery of monochorionic-diamniotic twins. OBJECTIVE: This study aimed to compare perinatal and maternal outcomes of planned cesarean delivery and planned vaginal delivery of monochorionic-diamniotic twins using the Twin Birth Study data. STUDY DESIGN: This study is a secondary analysis of the Twin Birth Study. Women were randomized from 32 weeks and 0 days gestation to 38 weeks and 6 days gestation to planned cesarean delivery or planned vaginal delivery. Twin A in the cephalic presentation and estimated weight of each twin between 1500 and 4000 grams were the inclusion criteria. Pregnancies complicated by fetal reduction after 13 weeks of gestation, lethal fetal anomaly, or contraindication to vaginal delivery were excluded. Elective delivery was planned between 37 weeks and 5 to 7 days of gestation and 38 weeks and 6 to 7 days of gestation. Perinatal and maternal outcomes of monochorionic-diamniotic twin pregnancies were compared between those randomized for planned cesarean delivery and those randomized for planned vaginal delivery. In addition, outcomes of monochorionic-diamniotic twin pregnancies were compared with those of dichorionic-diamniotic twin pregnancies. RESULTS: Out of the 1393 women in each arm, 346 (24.9%) women in the planned cesarean delivery arm and 324 (23.3%) women in the planned vaginal delivery arm had monochorionic-diamniotic twin pregnancies and were eligible for the first analysis. The rate of cesarean delivery was 39.2% in the planned vaginal delivery arm and was 91.3% in the planned cesarean delivery arm. There was no significant difference in gestational age at delivery between the groups (34.4±1.8 weeks vs 34.5±1.8 weeks; P=.78). No difference was found in maternal outcomes. As for perinatal outcomes, the rate of the primary adverse neonatal composite outcomes in twins A or twins B was similar in both the planned vaginal delivery and the planned cesarean delivery arms (twins A, 1.2% vs 1.2% [P=.92]; twins B, 1.2% vs 3.2% [P=.09]). Within the planned cesarean delivery arm, the rate of primary adverse neonatal composite outcome was higher in twins B than twins A (3.2% vs 1.2%; P=.03). There was no difference in the primary adverse neonatal composite outcome between twins A in the monochorionic-diamniotic group and the dichorionic-diamniotic group (1.2% vs 1.3%; P=.89) or between twins B in similar groups (2.3% vs 2.7%; P=.47). CONCLUSION: In monochorionic-diamniotic twin pregnancy between 32 weeks and 0 to 7 days of gestation and 38 weeks and 6 to 7 days of gestation, with twin A in a cephalic presentation, planned cesarean delivery did not decrease or increase the risk of fetal or neonatal death or serious neonatal morbidity, as compared with planned vaginal delivery.

The effect of the implementation of institutional checklist on expert opinion of oxytocin use in labor.

PURPOSE: Oxytocin is a commonly used drug in the labor and delivery unit. There are wide variations in oxytocin use between countries and medical centers, which may reflect the lack of structured guidelines. The aim of our study was to evaluate the need of oxytocin checklist in labor and delivery unit, while assessing the management of oxytocin with and without such a checklist. METHODS: This study was conducted in a single, university-affiliated medical center in two phases: before and after the implementation of an oxytocin checklist in the labor and delivery unit (2016-2017). Six experts reviewed cardiotocographs of deliveries performed in an urgent Cesarean delivery due to non-reassuring fetal heart rate, after completing at least 4 h of oxytocin infusion for induction or augmentation of labor. The experts included three obstetricians, a midwife, and two obstetrical expert nurses, who were tasked to conclude whether oxytocin was managed properly or not. Each case was reviewed by two reviewers separately. A total of 100 cases were reviewed; 50 before the oxytocin checklist implementation, and 50 after that implementation. RESULTS: We did not find a difference in the reviewers' assessment of oxytocin management before and after the institutional implementation of the checklist. Additionally, there were significant inconsistencies and inter-observer variations in their assessment before and after the checklist implementation. CONCLUSION: The implementation of an institutional oxytocin checklist did not affect expert assessment of the use of oxytocin in labor.

The worst of both worlds-combined deliveries in twin gestations: a subanalysis of the Twin Birth Study, a randomized, controlled, prospective study.

OBJECTIVE: The reported incidence of combined twin delivery (vaginal delivery of twin A followed by cesarean delivery for twin B) ranges between 5% and 10%. These estimates are based mostly on small studies or retrospective data. We aimed to evaluate to incidence and risk factors for and outcomes of combined twin deliveries, using a subanalysis of the Twin Birth Study, a randomized, controlled, prospective study. STUDY DESIGN: The Twin Birth Study included women with twin gestation between 32+0 and 38+6 weeks, with the first twin in vertex presentation at randomization. Women were randomized to planned cesarean delivery or planned vaginal delivery. For the purpose of this subanalysis, we included women who had a vaginal delivery of twin A. Women who had a combined delivery (cesarean delivery for twin B) were compared with women who had a vaginal delivery of both twins. Our primary objective was to identify risk factors for combined twin deliveries. Our secondary objective was to assess the rate of fetal/neonatal death or serious neonatal morbidity in combined deliveries. RESULTS: Of the 2786 women included in the original study, 842 women delivered twin A by a vaginal delivery and were included in the current analysis, of whom 59 (7%) had a combined delivery. Women in the combined delivery group had a lower rate of nulliparity (22.0% vs 34.7%, P = 0.047) and higher rates of noncephalic presentation of twin B at delivery (61.0% vs 27.3%, P < 0.001) and spontaneous version from presentation at randomization of twin B (72.9% vs 44.3%, P < 0.0001). In a multivariable model, the only risk factor significantly associated with a combined delivery was transverse/oblique lie of twin B following delivery of twin A (adjusted odds ratio, 47.7; 95% confidence interval, 15.4-124.5). Twins B in the combined delivery group had a higher rate of fetal/neonatal death or serious neonatal morbidity (13.6% vs 2.3%, P < 0.001), 5-minute Apgar score <7, neonatal intensive care unit admission, abnormal level of consciousness, and assisted ventilation. CONCLUSION: Transverse/oblique lie of twin B following vaginal delivery of twin A is a risk factor for combined delivery. Combined delivery is associated with higher risk of adverse neonatal outcomes of twin B. These data may be used to better counsel women with twin gestation who consider a trial of labor.

No. 382-Trial of Labour After Caesarean.

OBJECTIVE: To provide evidence-based guidelines for the provision of a trial of labour after Caesarean section. OUTCOMES: Fetal and maternal morbidity and mortality associated with vaginal birth after Caesarean and repeat Caesarean section. EVIDENCE: MEDLINE database was searched for articles published from January 1, 1995, to October 31, 2017 using the key words "vaginal birth after Caesarean (Cesarean) section." The quality of evidence is described using the Evaluation of Evidence criteria outlined in the Report of the Canadian Task Force on the Periodic Health Exam. VALIDATION: These guidelines were approved by the Clinical Practice Obstetrics Committee and the Board of the Society of Obstetricians and Gynaecologists of Canada.

Does prenatal identification of fetal macrosomia change management and outcome?

PURPOSE: To assess whether there is an association between predicted fetal macrosomia and adverse outcomes in macrosomic newborns (> 4000 g), based on a sonographic evaluation up to 2 weeks prior to delivery. METHODS: A retrospective cohort study of 3098 mothers of macrosomic babies who were delivered at our institution (2000-2015). We compared the management and outcomes of women with predicted fetal macrosomia with that of women with unknown fetal macrosomia. The primary outcomes were cesarean section (CS) rate and postpartum hemorrhage. Secondary outcomes were composite maternal and neonatal outcomes and birth injuries. RESULTS: In 601 (19.4%) women fetal macrosomia was predicted, and in 2497 (80.6%) women, fetal macrosomia was unknown. CS rate was more than 3.5 times higher in the group of predicted macrosomia (47.2% vs. 12.7%, P < 0.001) than those with unpredicted macrosomia; not only due to non-progressive labor, but for non-reassuring heart rate as well. However, predicted fetal macrosomia reduced the risk of postpartum hemorrhage (aOR 0.5, 95% CI 0.2-1.0), maternal (aOR 0.3, 95% CI 0.2-0.5) and neonatal composite adverse outcomes (aOR 0.7 95% CI 0.6-0.9). It was also associated with increased risk for induction of labor, episiotomy, 3rd- or 4th-degree tears and a longer maternal hospitalization. Birth injuries and shoulder dystocia were not different between the groups. CONCLUSIONS: Antepartum CS was found to be associated with predicted fetal macrosomia. Moreover, a planned CS due to macrosomia was associated with reduced risk for postpartum hemorrhage, maternal and neonatal outcome, even for babies with a mean birth weight < 4500 g.

A new care pathway to optimize gestational weight gain in twin pregnancies.

BACKGROUND: Maternal gestational weight gain is an important determinant of pregnancy outcomes and may have an even greater role in twin pregnancies because of their higher rate of pregnancy complications and greater nutritional demands. However, data on the optimal week-specific gestational weight gain in twin pregnancies and on interventions that should be applied in cases of inadequate gestational weight gain are limited. OBJECTIVE: This study aimed to determine whether a new care pathway that involves monitoring gestational weight gain using a week-specific chart, along with a standardized protocol for managing cases with inadequate gestational weight gain, can optimize maternal gestational weight gain in twin pregnancies. METHODS: In this study, patients with twin pregnancies followed in a single tertiary center between February 2021 and May 2022 were exposed to the new care pathway (postintervention group). Gestational weight gain and clinical outcomes were compared with those of a previously described cohort of patients with twins followed in our clinic before the implementation of the new care pathway (preintervention group). The new care pathway targeted patients and care providers and included educational material, a newly developed body mass index group-specific gestational weight gain chart, and a stepwise management algorithm in cases of inadequate gestational weight gain. The body mass index group-specific gestational weight gain charts were divided into 3 zones: (1) green zone (optimal gestational weight gain at 25th-75th centiles); (2) yellow zone (suboptimal gestational weight gain at 5th-24th or 76th-95th centiles); and (3) gray zone (abnormal gestational weight gain, at <5th or >95th centile). The primary outcome was the overall proportion of patients achieving optimal gestational weight gain at birth. RESULTS: A total of 123 patients were exposed to the new care pathway and were compared with 1079 patients from the preintervention period. Patients in the postintervention group were more likely to achieve optimal gestational weight gain at birth (60.2% vs 47.7%; adjusted odds ratio, 1.91; 95% confidence interval, 1.28-2.86) and were less likely to achieve low-suboptimal gestational weight gain (7.3% vs 14.7%; adjusted odds ratio, 0.41; 95% confidence interval, 0.20-0.85) or any suboptimal gestational weight gain (26.8% vs 34.8%; adjusted odds ratio, 0.60; 95% confidence interval, 0.39-0.93) at birth. In addition, patients in the postintervention group were less likely to have low-abnormal gestational weight gain anytime during gestation (18.9% vs 29.1%; P=.017) and were more likely to have normal gestational weight gain throughout pregnancy (21.3% vs 14.0%; P=.031) or high-abnormal gestational weight gain anytime during gestation (18.0% vs 11.1%; P=.025), suggesting that in comparison with standard care, the new care pathway is more effective in preventing patients from moving into the low-abnormal zone than the high-abnormal zone. Furthermore, the new care pathway was more effective than standard care in correcting high-suboptimal gestational weight gain and high-abnormal gestational weight gain. CONCLUSION: Our findings suggest that the new care pathway may be effective in optimizing maternal gestational weight gain in twin gestations, which may in turn contribute to better clinical outcomes. This is a simple, low-cost intervention that can be easily disseminated among providers caring for patients with twin pregnancies.

Reproductive health and pregnancy experiences of women with spina bifida: A qualitative study.

PURPOSE: Despite an increasing number of individuals with spina bifida reaching reproductive age, there has been a paucity of research into their reproductive health care needs. The objective of this study was to better understand the reproductive health experiences of self-identified women with spina bifida using qualitative methodology. METHODS: A phenomenological study design was used to address this objective. Women with spina bifida identified their interest in participating in a semi-structured interview after completing an online reproductive health survey. Interviews were recorded and transcribed verbatim. Qualitative analysis followed a phenomenological approach using Dedoose software. RESULTS: Twelve self-identified women with spina bifida participated. They described experiences in four domains: sexual education, pregnancy, labor and delivery, and postpartum. In addition, an intersecting domain of social justice and advocacy emerged. Numerous themes are described, including a lack of tailored sexual health information, impact of pregnancy on function, attitudes towards delivery method, and parenting challenges. CONCLUSION: This study explored the continuum of reproductive health experiences of women with spina bifida. They face unique reproductive health challenges that provide an opportunity for health care providers to offer more holistic care.

Delivery of the Nonpresenting Twin First: Rates and Associated Factors.

OBJECTIVE: To estimate the rate of delivery of the nonpresenting twin first and to identify risk factors for such an event by using a cohort of opposite-sex twins for whom the intrauterine order was well documented with ultrasonography before delivery. METHODS: We conducted a retrospective cohort study of all opposite-sex dichorionic twins in a single tertiary center between 2002 and 2016. Reports of ultrasonograms performed less than 2 weeks before birth were reviewed for information on twins' presenting order in relation to fetal sex. Intrauterine labeling was compared with labeling at the time of birth. Multivariable regression analysis was used to identify factors associated with delivery of the nonpresenting twin first. RESULTS: Of 1,746 women with dichorionic twin pregnancies, 942 (53.9%) had opposite-sex twins and 617 had recent data on ultrasonographic twin labeling. In 456 of 617 (73.9%) pregnancies, both twins were delivered by cesarean delivery and in 161 of 617 (26.1%) pregnancies, one or both twins were delivered vaginally. The overall rate of delivery of the nonpresenting twin first was 6.8% (95% CI 4.5-9.1%, 31/456) in the cesarean group; there were no deliveries (95% CI 0.0-2.3%, 0/161) of the nonpresenting twin first in the vaginal group (P=.001). The following factors were independently associated with delivery of the nonpresenting twin first at cesarean delivery: discordance greater than 25% in birth weights (17.5%, adjusted odds ratio [OR] 4.0, 95% CI 1.7-9.1), nonvertex presentation of the presenting twin (11.6%, adjusted OR 3.8, 95% CI 1.7-8.3), and gestational age less than 32 0/7 weeks (14.9%, adjusted OR 3.6, 95% CI 1.6-7.8). CONCLUSIONS: Delivery of the nonpresenting twin first in dichorionic, opposite-sex twins at the time of birth occurs in 6.8% of cesarean deliveries. Clinicians and researchers should be aware of this phenomenon because it has implications for neonatal care and long-term outcome.