Risk of intrapartum cesarean delivery in twin pregnancies: A retrospective cohort study

OBJECTIVE

To compare the risk of intrapartum cesarean delivery (CD) between patients with twin and singleton pregnancies undergoing a trial of labor and identify risk factors for intrapartum CD in twin pregnancies.

METHODS

The present study was a retrospective cohort study of patients with a twin or singleton pregnancy who underwent a trial of labor at ≥340/7 weeks in a single center (2015-2022). The primary outcome was the rate of intrapartum CD. In twin pregnancies, this outcome was limited to CD of both twins. The association of plurality with intrapartum CD was estimated using multivariable Poisson regression.

RESULTS

A total of 20 754 patients met the study criteria, 669 of whom had a twin pregnancy. Patients with twins had a greater risk of intrapartum CD (of both twins) than those with singleton pregnancies (22.1% vs 15.9%, respectively; aRR 1.38 [95% CI: 1.15-1.66]), primarily due to a greater risk of failure to progress. In addition, 4.1% of the twin pregnancies had a CD for the second twin, resulting in an overall CD rate in twin pregnancies of 26.2%. Variables associated with intrapartum CD in twin pregnancies included nulliparity (aOR 3.50, 95% CI: 2.34-5.25), birthweight discordance >20% (aOR 2.47, 95% CI: 1.27-4.78), and labor induction (aOR 1.64, 95% CI: 1.07-2.53). The rate of intrapartum CD was highest when all three risk factors were present (67% [95% CI: 41%-87%]).

CONCLUSION

Twin pregnancies are associated with a greater risk of intrapartum CD than singleton pregnancies. Information on the individualized risk of intrapartum CD may be valuable when counseling patients with twins regarding mode of delivery.

National and international guidelines on the management of twin pregnancies: a comparative review

Twin gestations are associated with increased risk of pregnancy complications. However, high-quality evidence regarding the management of twin pregnancies is limited, often resulting in inconsistencies in the recommendations of various national and international professional societies. In addition, some recommendations related to the management of twin gestations are often missing from the clinical guidelines dedicated to twin pregnancies and are instead included in the practice guidelines on specific pregnancy complications (eg, preterm birth) of the same professional society. This can make it challenging for care providers to easily identify and compare recommendations for the management of twin pregnancies. This study aimed to identify, summarize, and compare the recommendations of selected professional societies from high-income countries on the management of twin pregnancies, highlighting areas of both consensus and controversy. We reviewed clinical practice guidelines of selected major professional societies that were either specific to twin pregnancies or were focused on pregnancy complications or aspects of antenatal care that may be relevant for twin pregnancies. We decided a priori to include clinical guidelines from 7 high-income countries (United States, Canada, United Kingdom, France, Germany, and Australia and New Zealand grouped together) and from 2 international societies (International Society of Ultrasound in Obstetrics and Gynecology and the International Federation of Gynecology and Obstetrics). We identified recommendations regarding the following care areas: first-trimester care, antenatal surveillance, preterm birth and other pregnancy complications (preeclampsia, fetal growth restriction, and gestational diabetes mellitus), and timing and mode of delivery. We identified 28 guidelines published by 11 professional societies from the 7 countries and 2 international societies. Thirteen of these guidelines focus on twin pregnancies, whereas the other 16 focus on specific pregnancy complications predominantly in singletons but also include some recommendations for twin pregnancies. Most of the guidelines are recent, with 15 of the 29 guidelines published over the past 3 years. We identified considerable disagreement among guidelines, primarily in 4 key areas: screening and prevention of preterm birth, using aspirin to prevent preeclampsia, defining fetal growth restriction, and the timing of delivery. In addition, there is limited guidance on several important areas, including the implications of the "vanishing twin" phenomenon, technical aspects and risks of invasive procedures, nutrition and weight gain, physical and sexual activity, the optimal growth chart to be used in twin pregnancies, the diagnosis and management of gestational diabetes mellitus, and intrapartum care.This consolidation of key recommendations across several clinical practice guidelines can assist healthcare providers in accessing and comparing recommendations on the management of twin pregnancies and identifies high-priority areas for future research based on either continued disagreement among societies or limited current evidence to guide care.

A prediction tool for mode of delivery in twin pregnancies-a secondary analysis of the Twin Birth Study

BACKGROUND

One of the controversies regarding the management of twin gestations relates to the mode of delivery. Currently, counseling regarding the mode of delivery and the chance of successful vaginal twin delivery is based on the average risk for intrapartum cesarean delivery in the general population of twin pregnancies. Decision support tools that provide an individualized risk for intrapartum cesarean delivery based on the unique characteristics of each patient can improve counseling and decision-making regarding the choice of mode of delivery in twin pregnancies.

OBJECTIVE

This study aimed to develop and validate a prediction model to determine the risk for intrapartum cesarean delivery in twin pregnancies.

STUDY DESIGN

In this secondary analysis of the Twin Birth Study, a multicenter randomized controlled trial, we considered the subgroup of individuals who underwent a trial of vaginal delivery. Candidate predictors included maternal age, parity, previous cesarean delivery, conception method, chorionicity, diabetes and hypertension in pregnancy, gestational age at birth, the onset of labor, presentation of the second twin, sonographic fetal weight estimation, and fetal sex. The co-primary outcomes were overall intrapartum cesarean delivery and cesarean delivery of the second twin. Multivariable logistic regression models were used to estimate the probability of the study outcomes. Model performance was evaluated using measures of discrimination (the area under the receiver operating characteristic curve), calibration, and predictive accuracy. Internal validation was performed using the bootstrap resampling technique.

RESULTS

A total of 1221 individuals met the study criteria. The rate of overall intrapartum cesarean delivery and cesarean delivery for the second twin was 25.4% and 5.7%, respectively. The most contributory predictor variables were nulliparity, term birth (≥37 weeks), a noncephalic presentation of the second twin, previous cesarean delivery, and labor induction. The models for overall intrapartum cesarean delivery and cesarean delivery of the second twin had good overall discriminatory accuracy (area under the receiver operating characteristic curve, 0.720; 95% confidence interval, 0.688-0.752 and 0.736; 95% confidence interval, 0.669-0.803, respectively) and calibration (as illustrated by the calibration plot and Brier scores of 0.168; 95% confidence interval, 0.156-0.180 and 0.051; 95% confidence interval, 0.040-0.061, respectively). The models achieved good specificity (66.7% and 81.6%, respectively), high negative predictive value (86.0% and 96.9%, respectively), and moderate sensitivity (68.1% and 57.1%, respectively).

CONCLUSION

The prediction models developed in this study may assist care providers in counseling individuals regarding the optimal timing and mode of delivery in twin pregnancies by providing individualized estimates of the risk for intrapartum cesarean delivery.

Maternal First-Trimester Alpha-Fetoprotein and Placenta-Mediated Pregnancy Complications

BACKGROUND

Maternal serum markers used for trisomy 21 screening are associated with placenta-mediated complications. Recently, there has been a transition from the traditional first-trimester screening (FTS) that included PAPP-A (pregnancy-associated plasma protein-A) and beta-hCG (human chorionic gonadotropin), to the enhanced FTS test, which added first-trimester AFP (alpha-fetoprotein) and PlGF (placental growth factor). However, whether elevated first-trimester AFP has a similar association with placenta-mediated complications to that observed for elevated second-trimester AFP remains unclear. Our objective was to estimate the association of first-trimester AFP with placenta-mediated complications and compare it with the corresponding associations of second-trimester AFP and other first-trimester serum markers.

METHODS

Retrospective population-based cohort study of women who underwent trisomy 21 screening in Ontario, Canada (2013-2019). The association of first-trimester AFP with placenta-mediated complications was estimated and compared with that of the traditional serum markers. The primary outcome was a composite of stillbirth or preterm placental complications (preeclampsia, birthweight less than third centile, or placental abruption).

RESULTS

A total of 244 990 and 96 167 women underwent FTS and enhanced FTS test screening, respectively. All markers were associated with the primary outcome, but the association for elevated first-trimester AFP (adjusted relative risk [aRR], 1.57 [95% CI, 1.37-1.81]) was weaker than that observed for low PAPP-A (aRR, 2.48 [95% CI, 2.2-2.8]), low PlGF (aRR, 2.28 [95% CI, 1.97-2.64]), and elevated second-trimester AFP (aRR, 1.97 [95% CI, 1.81-2.15]). When the models were adjusted for all 4 enhanced FTS test markers, elevated first-trimester AFP was no longer associated with the primary outcome (aRR, 0.77 [95% CI, 0.58-1.02]).

CONCLUSIONS

Unlike second-trimester AFP, elevated first-trimester AFP is not an independent risk factor for placenta-mediated complications.

The smaller firstborn: exploring the association of parity and fetal growth

PURPOSE

To investigate the association of parity with a range of neonatal anthropometric measurements in a cohort of uncomplicated term singleton pregnancies.

METHODS

Retrospective cohort study of patients with a singleton term birth at a single tertiary center (2014-2020) was carried out. The primary exposure was parity. The following neonatal anthropometric measures were considered: birthweight, head circumference, length, ponderal index, and neonatal body mass index (BMI).

RESULTS

A total of 8134 patients met the study criteria, 1949 (24.0%) of whom were nulliparous. Compared with multiparous patients, infants of nulliparous patients had a lower mean percentile for birthweight (43.1 ± 26.4 vs. 48.3 ± 26.8 percentile, p < 0.001), head circumference (44.3 ± 26.4 vs. 48.1 ± 25.5 percentile, p < 0.001), length (52.6 ± 25.1 vs. 55.5 ± 24.6 percentile, p < 0.001), ponderal index (34.4 ± 24.0 vs. 37.6 ± 24.2 percentile, p < 0.001), and BMI (39.1 ± 27.1 vs. 43.9 ± 27.3 percentile, p < 0.001). In addition, infants of nulliparous patients had higher odds of having a small (< 10th percentile for gestational age) birthweight (aOR 1.32 [95% CI 1.12-1.56]), head circumference (aOR 1.54 [95% CI 1.29-1.84]), length (aOR 1.50 [95% CI 1.16-1.94]), ponderal index (aOR 1.30 [95% CI 1.12-1.51]), and body mass index (aOR 1.42 [95% CI 1.22-1.65]). Most neonatal anthropometric measures increased with parity until a parity of 2, where it seemed to reach a plateau.

CONCLUSION

Parity has an independent impact on a wide range of neonatal anthropometric measures, suggesting that parity is associated with both fetal skeletal growth and body composition. In addition, the association of parity with fetal growth does not follow a continuous relationship but instead reaches a plateau after the second pregnancy.

Directive clinique no 440 : Prise en charge de la grossesse gémellaire monochoriale

OBJECTIF

Cette directive clinique passe en revue les données probantes sur la prise en charge de la grossesse gémellaire monochoriale normale et compliquée.

POPULATION CIBLE

Les femmes menant une grossesse gémellaire ou multiple de haut rang. BéNéFICES, RISQUES ET COûTS: L'application des recommandations de cette directive devrait améliorer la prise en charge des grossesses gémellaires (ou multiples de haut rang) monochoriales compliquées et non compliquées. Ces recommandations aideront les fournisseurs de soins à surveiller adéquatement les grossesses gémellaires monochoriales ainsi qu'à détecter et prendre en charge rapidement les complications associées de façon optimale afin de réduire les risques de morbidité et mortalité périnatales. Ces recommandations impliquent une surveillance échographique plus fréquente en cas de grossesse monochoriale qu'en cas de grossesse bichoriale. DONNéES PROBANTES: La littérature publiée a été colligée par des recherches dans les bases de données PubMed et Cochrane Library au moyen de termes MeSH pertinents (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Les résultats ont été restreints aux revues systématiques, aux essais cliniques randomisés et aux études observationnelles. Aucune date limite n'a été appliquée, mais les résultats ont été limités aux contenus en anglais ou en français. MéTHODES DE VALIDATION: Les auteurs principaux ont rédigé le contenu et les recommandations et ils se sont entendus sur ces derniers. Le conseil d'administration de la SOGC a approuvé la version définitive aux fins de publication. Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations Assessment, Development and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et conditionnelles [faibles]). PROFESSIONNELS CONCERNéS: Spécialistes en médecine fœto-maternelle, obstétriciens, radiologues, échographistes, médecins de famille, infirmières, sages-femmes, résidents et autres fournisseurs de soins de santé qui s'occupent de femmes menant une grossesse gémellaire ou multiple de haut rang. RéSUMé POUR TWITTER: Directive canadienne (SOGC) pour le diagnostic, la surveillance échographique et la prise en charge des complications de la grossesse gémellaire monochoriale (p. ex., STT, TAPS, retard de croissance sélectif, cojumeau acardiaque, monoamnionicité et mort d'un jumeau). DÉCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Prediction of birthweight and risk of macrosomia in pregnancies complicated by diabetes

BACKGROUND

Antenatal detection of accelerated fetal growth and macrosomia in pregnancies complicated by diabetes mellitus is important for patient counseling and management. Sonographic fetal weight estimation is the most commonly used tool to predict birthweight and macrosomia. However, the predictive accuracy of sonographic fetal weight estimation for these outcomes is limited. In addition, an up-to-date sonographic fetal weight estimation is often unavailable before birth. This may result in a failure to identify macrosomia, especially in pregnancies complicated by diabetes mellitus where care providers might underestimate fetal growth rate. Therefore, there is a need for better tools to detect and alert care providers to the potential risk of accelerated fetal growth and macrosomia.

OBJECTIVE

This study aimed to develop and validate prediction models for birthweight and macrosomia in pregnancies complicated by diabetes mellitus.

STUDY DESIGN

This was a completed retrospective cohort study of all patients with a singleton live birth at ≥36 weeks of gestation complicated by preexisting or gestational diabetes mellitus observed at a single tertiary center between January 2011 and May 2022. Candidate predictors included maternal age, parity, type of diabetes mellitus, information from the most recent sonographic fetal weight estimation (including estimated fetal weight, abdominal circumference z score, head circumference-to-abdomen circumference z score ratio, and amniotic fluid), fetal sex, and the interval between ultrasound examination and birth. The study outcomes were macrosomia (defined as birthweights >4000 and >4500 g), large for gestational age (defined as a birthweight >90th percentile for gestational age), and birthweight (in grams). Multivariable logistic regression models were used to estimate the probability of dichotomous outcomes, and multivariable linear regression models were used to estimate birthweight. Model discrimination and predictive accuracy were calculated. Internal validation was performed using the bootstrap resampling technique.

RESULTS

A total of 2465 patients met the study criteria. Most patients had gestational diabetes mellitus (90%), 6% of patients had type 2 diabetes mellitus, and 4% of patients had type 1 diabetes mellitus. The overall proportions of infants with birthweights >4000 g, >4500 g, and >90th percentile for gestational age were 8%, 1%, and 12%, respectively. The most contributory predictor variables were estimated fetal weight, abdominal circumference z score, ultrasound examination to birth interval, and type of diabetes mellitus. The models for the 3 dichotomous outcomes had high discriminative accuracy (area under the curve receiver operating characteristic curve, 0.929-0.979), which was higher than that achieved with estimated fetal weight alone (area under the curve receiver operating characteristic curve, 0.880-0.931). The predictive accuracy of the models had high sensitivity (87%-100%), specificity (84%-92%), and negative predictive values (84%-92%). The predictive accuracy of the model for birthweight had low systematic and random errors (0.6% and 7.5%, respectively), which were considerably smaller than the corresponding errors achieved with estimated fetal weight alone (-5.9% and 10.8%, respectively). The proportions of estimates within 5%, 10%, and 15% of the actual birthweight were high (52.3%, 82.9%, and 94.9%, respectively).

CONCLUSION

The prediction models developed in the current study were associated with greater predictive accuracy for macrosomia, large for gestational age, and birthweight than the current standard of care that includes estimated fetal weight alone. These models may assist care providers in counseling patients regarding the optimal timing and mode of delivery.

Guideline No. 440: Management of Monochorionic Twin Pregnancies

OBJECTIVE

This guideline reviews the evidence-based management of normal and complicated monochorionic twin pregnancies.

TARGET POPULATION

Women with monochorionic twin or higher order multiple pregnancies.

BENEFITS, HARMS, AND COSTS

Implementation of these recommendations should improve the management of both complicated and uncomplicated monochorionic (and higher order multiple) twin pregnancies. They will help users monitor monochorionic twin pregnancies appropriately and identify and manage monochorionic twin complications optimally in a timely manner, thereby reducing perinatal morbidity and mortality. These recommendations entail more frequent ultrasound monitoring of monochorionic twins compared to dichorionic twins.

EVIDENCE

Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate MeSH headings (Twins, Monozygotic; Ultrasonography, Prenatal; Placenta; Fetofetal Transfusion; Fetal Death; Fetal Growth Retardation). Results were restricted to systematic reviews, randomized controlled clinical trials, and observational studies. There were no date limits, but results were limited to English or French language materials.

VALIDATION METHODS

The content and recommendations were drafted and agreed upon by the principal authors. The Board of the SOGC approved the final draft for publication. The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Maternal-fetal medicine specialists, obstetricians, radiologists, sonographers, family physicians, nurses, midwives, residents, and other health care providers who care for women with monochorionic twin or higher order multiple pregnancies.

TWEETABLE ABSTRACT

Canadian (SOGC) guidelines for the diagnosis, ultrasound surveillance and management of monochorionic twin pregnancy complications, including TTTS, TAPS, sFGR (sIUGR), acardiac (TRAP), monoamniotic twins and intrauterine death of one MC twin.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Mild neonatal morbidity in twins by planned mode of delivery: a secondary analysis of the Twin Birth Study

BACKGROUND

The Twin Birth Study showed no differences in major severe adverse neonatal outcomes between those with planned vaginal delivery and those with planned cesarean delivery.

OBJECTIVE

This was a secondary analysis of the Twin Birth Study in which mild neonatal morbidities, not previously reported, were compared between parturients with planned cesarean deliveries and those with planned vaginal delivery in twin births.

STUDY DESIGN

This was a secondary analysis of the Twin Birth Study. In this study, women with a twin pregnancy at 32+0/7 to 38+6/7 weeks of gestation with the first twin in cephalic presentation and with an estimated weight between 1500 and 4000 g were randomized to either planned cesarean delivery or planned vaginal delivery. The primary outcome of this study was a composite mild neonatal outcome of respiratory and neurologic morbidities and neonatal intensive care unit admission that were not reported in the original Twin Birth Study at 34+0/7 to 38+6/7 weeks of gestation. A multivariable logistic regression analysis was used to identify factors associated with the composite adverse neonatal outcomes. Neonatal outcomes were further stratified by gestational age at delivery and by actual mode of delivery.

RESULTS

A total of 1304 women and 1326 women were randomly assigned to planned cesarean delivery and planned vaginal delivery, respectively. Demographic and obstetrical characteristics were similar between the study groups. The rate of cesarean delivery was 90.1% in the planned cesarean delivery group and 40.1% in the planned vaginal delivery group. There was no significant difference in the primary composite outcome between the groups (10.6% vs 11.3%; P=.45) neither by planned mode of delivery nor by actual mode of delivery. Stratification by gestational age found a lower rate of the primary outcomes at ≥38+0/7 weeks of gestation in the planned cesarean delivery group when compared with the planned vaginal delivery group (4.8% vs 10.8%, respectively; P=.02). Furthermore, a lower risk for some individual outcomes was reported in the planned cesarean delivery group when compared with the planned vaginal delivery group, including intraventricular hemorrhage stage 1 to 2 (0.2% vs 0.6%; P<.05), low Apgar scores (0.8% vs 2.3%; P<.05), pH <7.0 (0.3 vs 1%; P<.05), and assisted ventilation needed at delivery (0.4% vs 0.9%; P<.05).

CONCLUSION

In twin deliveries, with the first twin in the cephalic presentation, composite mild neonatal morbidity was not affected by the planned mode of delivery. These findings reinforce the original results of the Twin Birth Study. Nevertheless, an increased composite outcome after 38 weeks' gestation and a higher risk for some individual morbidities in the planned vaginal delivery group might be viewed as a concerning signal for the safety of vaginal delivery in twin deliveries and requires further research.

The Course and Neonatal Outcome of Choroid Plexus Extension to the Anterior Horn at the Routine Anatomy Scan

OBJECTIVES

Our objective was to examine the pregnancy course and immediate neonatal outcome of fetuses with an isolated extension of choroid plexus (CP) to the anterior horn during the second trimester.

METHODS

We prospectively collected the cases referred to us between July 2012 and January 2021 with isolated finding of CP extension to the anterior horn. Relevant clinical and demographic information was recorded, and a full anatomy scan including a comprehensive neurosonogram was performed. In cases of confirmed isolated extension of CP to the anterior horns, women were offered further investigation including fetal MRI, and ultrasound follow up.

RESULTS

We collected 29 eligible cases for analysis. The mean gestational age (GA ± SD) for diagnosis and referral was 19.24 ± 2.3 weeks. No other intracranial anomalies were detected in any of the cases, and the finding resolved at 25 ± 2.6 weeks. The average extension length and width to the anterior horn were 0.7 ± 0.3 cm, and 0.5 ± 0.1 cm, respectively. Eleven fetuses (38%) had choroid plexus cyst (CPC) in addition to the extension. Ten patients (35%) completed a fetal brain MRI, with no identified abnormalities. Gross neurological exam and Apgar score at birth were normal.

CONCLUSION

Extension of CP to anterior horn with or without CPC at mid-trimester seems to have spontaneous resolution with likely a good prognosis and no further implications.

Coordinating smoking cessation treatment with menstrual cycle phase to improve quit outcomes (MC-NRT): study protocol for a randomized controlled trial

BACKGROUND

Women experience greater difficulty achieving smoking abstinence compared to men. Recent evidence suggests that hormonal fluctuations during different phases of the menstrual cycle can contribute to lower smoking abstinence rates following a quit attempt among women. However, these findings are limited by small sample sizes and variability among targeted smoking quit dates. This clinical trial aims to clarify whether targeting the quit date to the follicular or luteal phase of the menstrual cycle can improve smoking abstinence.

METHODS

Participants will enroll in an online smoking cessation program providing nicotine replacement therapy (NRT) and behavioral support. We will randomize 1200 eligible individuals to set a target quit date: (1) during the mid-luteal phase, (2) during the mid-follicular phase, or (3) 15-30 days after enrollment with no regard to the menstrual cycle phase (usual practice). Participants will receive a 6-week supply of combination NRT consisting of a nicotine patch plus their choice of nicotine gum or lozenge. Participants will be instructed to start using NRT on their target quit date. Optional behavioral support will consist of a free downloadable app and brief videos focusing on building a quit plan, coping with cravings, and relapse prevention, delivered via e-mail. Smoking status will be assessed via dried blood spot analysis of cotinine concentration at 7 days, 6 weeks, and 6 months post-target quit date.

DISCUSSION

We aim to overcome the limitations of previous studies by recruiting a large sample of participants and assigning target quit dates to the middle of both the follicular and luteal phases. The results of the trial can further elucidate the effects of the menstrual cycle on smoking cessation outcomes and whether it is beneficial to combine menstrual cycle phase timing strategies with accessible and low-cost NRT.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05515354. Registered on August 23, 2022.

Prenatal screening for preeclampsia: the roles of PlGF and PAPP-A in the first trimester and PlGF and SFlt-1/PlGF ratio in the early second trimester

BACKGROUND

Professional societies have recommended universal first trimester screening for preeclampsia and a second or third trimester soluble fms-like tyrosine kinase-1-placental growth factor ratio test to assess for preeclampsia and its severity. However, it may not be feasible to implement the most optimal screening protocol for preeclampsia in the first trimester which uses a combination of maternal characteristics, maternal biophysical and biochemical markers due to limitations in the access to uterine artery doppler ultrasound. There are inconsistent findings on how early in the second trimester the fms-like tyrosine kinase-1-placental growth factor ratio begins to provide useful information in preeclampsia prediction.

OBJECTIVE

This study aimed to assess the accuracy of (1) a combination of maternal characteristics, maternal serum pregnancy-associated plasma protein A, and placental growth factor in the screening for preeclampsia in the first trimester; and (2) placental growth factor or soluble fms-like tyrosine kinase-1-placental growth factor ratio in the prediction of preeclampsia in the early second trimester.

STUDY DESIGN

This retrospective case-control study used frozen residual blood samples from women who had aneuploidy screening and delivered at a tertiary center. The case group included pregnancies with gestational hypertension or preeclampsia (further classified as early-onset [birth at <34 weeks' gestation] and preterm preeclampsia [birth at <37 weeks' gestation]). Each case was matched with 3 control pregnancies by date of blood sample draw, gestational age at first blood sample draw, maternal age, maternal ethnicity, type of multiple-marker screening, and amount of residual sample. Mann-Whitney U tests were used to assess the associations between serum markers and the risk of preeclampsia. Logistic regressions were used to assess if the risk of preeclampsia can be predicted using a combination of maternal characteristics and serum markers.

RESULTS

The case group included 146 preeclampsia and 295 gestational hypertension cases. Compared with the controls, preeclampsia cases had significantly lower first-trimester pregnancy-associated plasma protein A and placental growth factor. At a 20% false-positive rate, 71% of early-onset and 58% of preterm preeclampsia cases can be predicted using maternal characteristics, pregnancy-associated plasma protein A, and placental growth factor. Preeclampsia cases had lower second-trimester placental growth factor and a higher soluble fms-like tyrosine kinase-1-placental growth factor ratio. At a 10% false-positive rate, 80% and 53% of early-onset preeclampsia can be predicted using maternal characteristics and placental growth factor or soluble fms-like tyrosine kinase-1-placental growth factor ratio, respectively.

CONCLUSION

The current first-trimester aneuploidy screening programs may be expanded to identify women at increased risk of developing preeclampsia. Early in the second trimester, placental growth factor alone provided better prediction for preeclampsia compared with the soluble fms-like tyrosine kinase-1-placental growth factor ratio.

Trial of labor of vertex-nonvertex twins following a previous cesarean delivery

BACKGROUND

Maternal and neonatal outcomes of trial of labor after cesarean delivery of twins are similar to those of singleton trials of labor after cesarean delivery. However, previous studies did not stratify outcomes by second-twin presentation on admission to labor.

OBJECTIVE

To examine maternal and neonatal outcomes following trial of labor after cesarean delivery in twins with vertex-nonvertex presentation.

STUDY DESIGN

A retrospective multicenter study was conducted including data on deliveries occurring between the years 2005 and 2020. We included trials of labor after a previous cesarean delivery (at ≥32^0/7 weeks' gestation) of twin gestations with a vertex-presenting first twin on admission to labor. The exposed group was defined as deliveries with a nonvertex second twin at admission to labor, whereas the comparison group included deliveries with a vertex second twin at admission. Only parturients who attempted vaginal delivery were included. Cases of prelabor fetal death of either twin or major fetal anomalies were excluded. The primary outcome was uterine rupture.

RESULTS

A total of 236 twin trials of labor after cesarean delivery were included, of which 128 involved nonvertex second twins and 108 a second vertex twin. Uterine rupture rates were comparable between the groups (1/128 [0.9%] vs 1/108 [0.8%]; P=1.000). Successful trial of labor after cesarean delivery of both twins occurred in 76.6% of the exposed group vs 81.5% of the comparison group, whereas cesarean delivery of both twins was performed in 21.9% of the exposed group vs 17.6% of the comparison group (P=.418; odds ratio, 1.32; confidence interval, 0.7-2.5). Two cases of cesarean delivery of the second twin occurred in the exposed group and 1 in the comparison group (1.6% vs 0.9%, respectively, P=1.000). There was no difference between the groups in maternal outcomes, including rates of postpartum hemorrhage, blood transfusion, placental abruption, thromboembolic events, and maternal fever. Neonatal outcomes were also comparable between the groups, including rates of intensive care admission and low (≤7) 5-minute Apgar scores.

CONCLUSION

Our data show that trial of labor after cesarean delivery of noncephalic second twins holds favorable maternal and neonatal outcomes, comparable with those of vertex-vertex trials of labor after cesarean delivery. Second-twin noncephalic presentation should not discourage parturients and caregivers from considering trial of labor after cesarean delivery if desired.

Guideline No. 428: Management of Dichorionic Twin Pregnancies

OBJECTIVE

To review evidence-based recommendations for the management of dichorionic twin pregnancies.

TARGET POPULATION

Pregnant women with a dichorionic twin pregnancy.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in this guideline may improve the management of twin pregnancies and reduce neonatal and maternal morbidity and mortality.

EVIDENCE

Published literature was retrieved through searches of PubMed and the Cochrane Library using appropriate controlled vocabulary (e.g., twin, preterm birth). Results were restricted to systematic reviews, randomized controlled trials, controlled clinical trials, and observational studies. There were no date limits, but results were limited to English- or French-language materials.

VALIDATION METHODS

The content and recommendations were drafted and agreed upon by the principal authors. The Board of the SOGC approved the final draft for publication. The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and weak recommendations).

INTENDED AUDIENCE

Obstetricians, family physicians, nurses, midwives, maternal-fetal medicine specialists, radiologists, and other health care providers who care for women with twin pregnancies.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Modified multiple marker aneuploidy screening as a primary screening test for preeclampsia

Background

Abnormal levels of maternal biochemical markers used in multiple marker aneuploidy screening have been associated with adverse pregnancy outcomes. This study aims to assess if a combination of maternal characteristics and biochemical markers in the first and second trimesters can be used to screen for preeclampsia (PE). The secondary aim was to assess this combination in identifying pregnancies at risk for gestational hypertension and preterm birth.

Methods

This case-control study used information on maternal characteristics and residual blood samples from pregnant women who have undergone multiple marker aneuploidy screening. The median multiple of the median (MoM) of first and second trimester biochemical markers in cases (women with PE, gestational hypertension and preterm birth) and controls were compared. Biochemical markers included pregnancy-associated plasma protein A (PAPP-A), placental growth factor (PlGF), human chorionic gonadotropin (hCG), alpha feto-protein (AFP), unconjugated estriol (uE3) and Inhibin A. Logistic regression analysis was used to estimate screening performance using different marker combinations. Screening performance was defined as detection rate (DR) and false positive rate (FPR). Preterm and early-onset preeclampsia PE were defined as women with PE who delivered at < 37 and < 34 weeks of gestation, respectively.

Results

There were 147 pregnancies with PE (81 term, 49 preterm and 17 early-onset), 295 with gestational hypertension, and 166 preterm birth. Compared to controls, PE cases had significantly lower median MoM of PAPP-A (0.77 vs 1.10, p < 0.0001), PlGF (0.76 vs 1.01, p < 0.0001) and free-β hCG (0.81 vs. 0.98, p < 0.001) in the first trimester along with PAPP-A (0.82 vs 0.99, p < 0.01) and PlGF (0.75 vs 1.02, p < 0.0001) in the second trimester. The lowest first trimester PAPP-A, PlGF and free β-hCG were seen in those with preterm and early-onset PE. At a 20% FPR, 67% of preterm and 76% of early-onset PE cases can be predicted using a combination of maternal characteristics with PAPP-A and PlGF in the first trimester. The corresponding DR was 58% for gestational hypertension and 36% for preterm birth cases.

Conclusions

Maternal characteristics with first trimester PAPP-A and PlGF measured for aneuploidy screening provided reasonable accuracy in identifying women at risk of developing early onset PE, allowing triage of high-risk women for further investigation and risk-reducing therapy. This combination was less accurate in predicting women who have gestational hypertension or preterm birth.

Reassurance from second trimester sonographic placental scan for pregnancies complicated by abnormal first trimester biomarkers

OBJECTIVE

Enhanced first trimester aneuploidy screening (eFTS) combines serum biomarkers and ultrasound. Abnormal biomarkers are associated with placental complications, such as fetal growth restriction (FGR). We aimed to evaluate whether a Midtrimester placental scan can provide reassurance regarding FGR in women with abnormal eFTS biomarkers.

METHODS

We conducted a retrospective cohort study of women who had eFTS and delivered at a single referral center. Women with abnormal biomarkers had a mid-trimester scan of the placenta (morphologic assessment, fetal biometry and uterine artery pulsatility index). We compared pregnancies with abnormal eFTS biomarkers and normal placental scans (study group) with those who had normal eFTS biomarkers (control group).

RESULTS

A total of 6,514 women were included, of whom 343 (5.3%) comprised the study group. Women in the study group had an increased risk of hypertensive disorders of pregnancy [(aOR)1.96(95%CI 1.21-3.16)], and preterm birth <37 weeks [aOR1.98(95%CI 1.33-2.95)] compared to the control group. Yet, their neonates were not at higher risk for FGR <3^rd, 5^th, or 10^th percentile [aOR1.16(95%CI 0.83-1.63), 1.14(95%CI 0.70-1.87), and 0.47(95%CI 0.17-1.27), respectively].

CONCLUSION

A normal second trimester placental scan provided reassurance regarding the risk of FGR in women at high risk based on abnormal eFTS biomarkers.

Mode of delivery in multiple pregnancies

The mode of delivery in multiple pregnancies has been subject to vigorous debates during the last few decades. Although observational and retrospective data were accumulated, it was not until the publication of the Twin Birth Study that evidence-based recommendations could emerge. However, although some of the most pressing questions were answered by the Twin Birth Study, other questions were left outside the scope of the study. The questions were of great interest and included the following topics: the impact of gestational age, the influence of chorionicity, and the generalizability of the results for women with a previous uterine scar. The current evidence supported a trial of labor in dichorionic-diamniotic or monochorionic-diamniotic twin pregnancies in which the first twin is in cephalic presentation at ≥32 weeks' gestation. Dichorionic-diamniotic, monochorionic-diamniotic, and monochorionic-monoamniotic twins should be delivered at 37 0/7 to 38 0/7, 36 0/7 to 37 0/7, and 32 0/7 to 34 0/7 weeks' gestation, respectively. Breech extraction done by a competent healthcare provider seemed to offer a higher chance of successful vaginal delivery of the second twin than the external cephalic version. The current data did not allow for a clear recommendation regarding the mode of delivery in very preterm birth of low birthweight twins, but most studies did not demonstrate a clear benefit of cesarean delivery vs trial of labor. Furthermore, a trial of labor seemed safe in women with a previous cesarean delivery. Cesarean delivery is likely beneficial for twin pregnancies with the first twin in breech presentation, monochorionic-monoamniotic twins, and higher-order multiple pregnancies. In all multiple pregnancies, delivery should be performed by an experienced practitioner competent in multiple pregnancy deliveries.

Patterns of discordant growth and adverse neonatal outcomes in twins

BACKGROUND

Intertwin size discordance is an independent risk factor for adverse neonatal outcomes in twin pregnancies. However, size discordance at a given point in gestation fails to take into consideration information, such as the timing of onset and the rate of progression of discordance, that may be of prognostic value.

OBJECTIVE

In this study, we aimed to identify distinct patterns of discordant fetal growth in twin pregnancies and to determine whether these patterns are predictive of adverse pregnancy outcomes.

STUDY DESIGN

This was a retrospective cohort study of women with twin pregnancies in a single tertiary referral center between January 2011 and April 2020, who had at least 3 ultrasound examinations during pregnancy that included assessment of fetal biometry. Size discordance was calculated at each ultrasound examination, and pregnancies were classified into 1 of 4 predetermined patterns based on the timing of onset and the progression of discordance: pattern 1, no significant discordance group (referent); pattern 2, early (<24 weeks' gestation) progressive discordance group; pattern 3, early discordance with plateau group; or pattern 4, late (≥24 weeks' gestation) discordance group. The associations of discordance pattern (using pattern 1 as referent) with preterm birth, preeclampsia, size discordance at birth, and birthweight<10th percentile were expressed as adjusted relative risk with 95% confidence intervals and were compared with those observed for a single measurement of size discordance at 32 weeks' gestation.

RESULTS

Of 2075 women with a twin gestation who were identified during the study period, 1059 met the study criteria. Of the 1059 women, 599 (57%) were classified as no significant discordance (pattern 1), 23 (2%) as early progressive discordance (pattern 2), 160 (15%) as early discordance with plateau (pattern 3), and 277 (26%) as late discordance (pattern 4). The associations of discordance pattern with preterm birth at <34 weeks' gestation and preeclampsia were strongest for pattern 2 (rates of 43% [adjusted relative risk, 3.43; 95% confidence interval, 2.10-5.62] and 17% [adjusted relative risk, 5.81; 95% confidence interval, 2.31-14.60], respectively), intermediate for pattern 3 (rates of 23% [adjusted relative risk, 1.82; 95% confidence interval, 1.28-2.59] and 6% [adjusted relative risk, 2.08; 95% confidence interval, 1.01-4.43], respectively), and weakest for pattern 4 (rates of 12% [adjusted relative risk, 0.96; 95% confidence interval, 0.65-1.42] and 4% [adjusted relative risk, 1.41; 0.68-2.92], respectively). In contrast, a single measurement of size discordance at 32 weeks' gestation showed no association with preeclampsia and only a weak association with preterm birth at <34 weeks' gestation.

CONCLUSION

We identified 4 distinct discordance growth patterns among twins that demonstrated a dose-response relationship with adverse outcomes and seemed to be more informative than a single measurement of size discordance.

Diagnostic accuracy of fetal growth charts for placenta-related fetal growth restriction

INTRODUCTION

The choice of fetal growth chart to be used in antenatal screening for fetal growth restriction (FGR) has an important impact on the proportion of fetuses diagnosed as small for gestational age (SGA), and on the detection rate for FGR. We aimed to compare diagnostic accuracy of SGA diagnosed using four different common fetal growth charts [Hadlock, Intergrowth-21st (IG21), World Health Organization (WHO), and National Institute of Child Health and Human Development (NICHD)], for abnormal placental pathology.

METHODS

A secondary analysis of data from a prospective cohort study in low-risk nulliparous women. The exposure was SGA (birthweight <10th centile for gestational age) using each of the four charts. The outcomes were one of three types of abnormal placental pathology associated with fetal growth restriction: maternal vascular malperfusion (MVM), chronic villitis, and fetal vascular malperfusion.

RESULTS

A total of 742 nulliparous women met the study criteria. The proportion of SGA was closest to the expected rate of 10% using the Hadlock chart (12.7%). The detection rates (DR) and false positive rates (FPR) for MVM pathology were similar for the Hadlock (DR = 53.1%, FPR = 10.8%), WHO (DR = 59.4%, FPR = 14.2%), and NICHD (DR = 53.1%, FPR = 12.3%) charts, and each was superior when compared to the IG21 chart (DR = 34.4%, FPR = 3.8%, p < 0.001). The diagnosis of SGA was associated with increased risks of preeclampsia and preterm birth for all four charts.

DISCUSSION

The selection of fetal growth chart to be used in screening programs for FGR has important implications with regard to the false positive and detection rate for FGR.

Cesarean delivery or induction of labor in pre-labor twin gestations: a secondary analysis of the twin birth study

Background

In the Twin Birth Study, women at 32^0/7–38^6/7 weeks of gestation, in whom the first twin was in cephalic presentation, were randomized to planned vaginal delivery or cesarean section. The study found no significant differences in neonatal or maternal outcomes in the two planned mode of delivery groups. We aimed to compare neonatal and maternal outcomes of twin gestations without spontaneous onset of labor, who underwent induction of labor or pre-labor cesarean section as the intervention of induction may affect outcomes.

Methods

In this secondary analysis of the Twin Birth Study we compared those who had an induction of labor with those who had a pre-labor cesarean section. The primary outcome was a composite of fetal or neonatal death or serious neonatal morbidity. Secondary outcome was a composite of maternal morbidity and mortality. Trial Registration: NCT00187369.

Results

Of the 2804 women included in the Twin Birth Study, a total of 1347 (48%) women required a delivery before a spontaneous onset of labor occurred: 568 (42%) in the planned vaginal delivery arm and 779 (58%) in the planned cesarean arm. Induction of labor was attempted in 409 (30%), and 938 (70%) had a pre-labor cesarean section. The rate of intrapartum cesarean section in the induction of labor group was 41.3%. The rate of the primary outcome was comparable between the pre-labor cesarean section group and induction of labor group (1.65% vs. 1.97%; p = 0.61; OR 0.83; 95% CI 0.43–1.62). The maternal composite outcome was found to be lower with pre-labor cesarean section compared to induction of labor (7.25% vs. 11.25%; p = 0.01; OR 0.61; 95% CI 0.41–0.91).

Conclusion

In women with twin gestation between 32^0/7–38^6/7 weeks of gestation, induction of labor and pre-labor cesarean section have similar neonatal outcomes. Pre-labor cesarean section is associated with favorable maternal outcomes which differs from the overall Twin Birth Study results. These data may be used to better counsel women with twin gestation who are faced with the decision of interventional delivery.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-020-03369-x.

Neonatal outcome by planned mode of delivery in women with a body mass index of 35 or more: a retrospective cohort study

OBJECTIVE

To compare neonatal outcomes of women with a body mass index (BMI) of ≥35 kg/m² who underwent a trial of labour with those of women who underwent a planned primary caesarean section (CS).

DESIGN

A retrospective cohort study of births between April 2012 and March 2014.

SETTING

A provincial database: Better Outcomes Registry & Network (BORN) Ontario, Canada.

POPULATION

A cohort of 8752 women with a BMI of ≥35 kg/m² who had a singleton birth at 38-42 weeks of gestation.

METHODS

Neonatal outcomes were compared between women who underwent a trial of labour (with either a successful vaginal birth or intrapartum CS) and those who underwent a planned CS.

MAIN OUTCOME MEASURE

A composite of any of the following outcomes: intrapartum neonatal death, neonatal intensive care unit admission, 5-minute Apgar score of <7 or umbilical artery pH of <7.1.

RESULTS

During the study period, 8433 (96.4%) women had a trial of labour and 319 (3.6%) had a planned CS. Intrapartum CS was performed in 1644 (19.5%) cases. There was no association between planned mode of delivery and the primary outcome (aOR 0.80, 95% CI 0.59-1.07). The primary outcome was lower among women who had a successful trial of labour (aOR 0.67, 95% CI 0.50-0.91) and was higher among women who had a failed trial of labour (aOR 1.74, 95% CI 1.21-2.48), compared with women who underwent a planned CS.

CONCLUSIONS

In women with a BMI of ≥35 kg/m² at a gestational age of 38-42 weeks, neonatal outcomes are comparable between planned vaginal delivery and planned CS, although a failed trial of labour is at risk of adverse neonatal outcome.

TWEETABLE ABSTRACT

Neonatal outcomes are not affected by planned mode of delivery in women who are obese, with a BMI of ≥35 kg/m² .

Maternal Ethnicity and the Risk of Obstetrical Anal Sphincter Injury: A Retrospective Cohort Study

OBJECTIVE

To explore the role of maternal ethnicity as a risk factor for obstetrical anal sphincter injury (OASI).

METHODS

A retrospective cohort study of all women with singleton gestations who had a vaginal delivery at term, between January 2014 and October 2017, at a single center. OASI was defined as a third-degree perineal tear (anal sphincter complex) or a fourth-degree perineal tear (anorectal mucosa). The characteristics of women with and without OASIs were compared. Multiple logistic regression was performed to account for potential confounders, including ethnicity.

RESULTS

During the study period, 11 012 women were eligible for inclusion, of whom 336 (3.1%) had an OASI; 313 (93.1%) had a third-degree tear, and 23 (6.9%) had a fourth-degree tear. Women with OASIs were characterized by younger maternal age (<35 years), Asian ethnicity, nulliparity, neonatal birth weight ≥3500 grams, midline and mediolateral episiotomy, second stage of labour lasting ≥60 minutes, and assisted vaginal delivery. After adjusting for potential confounders, Asian ethnicity remained independently associated with increased risk of OASI (adjusted odds ratio 2.07; 95% CI 1.6-2.7) whereas mediolateral episiotomy was independently associated with decreased risk of OASI (adjusted odds ratio 0.64; 95% CI 0.5-0.9).

CONCLUSION

Asian ethnicity is independently associated with increased risk of OASI. Although midline episiotomy increases the risk of OASI, mediolateral episiotomy may protect against OASI, and should be considered in high-risk patients.

Lateral placentation and adverse perinatal outcomes

Lateral placentation may compromise placental perfusion, and we aimed to assess whether it impacts pregnancy outcomes. This single-center retrospective study included 1203 singleton pregnancies, categorized into two groups according to placental location. Women with lateral placenta had significantly higher risk of preterm birth <37 weeks (aOR 2.99) and <34 weeks (aOR 3.92), and gestational diabetes (aOR 2.72), compared to women with central placenta. Mean birth weight and small for gestational age (SGA) rates were similar between groups. Our findings suggest that lateral placenta may be associated with increased risk for preterm birth but not for SGA.

Comparing Foley Catheter to Prostaglandins for Cervical Ripening in Multiparous Women

OBJECTIVE

This study sought to test the hypothesis that among multiparous women requiring cervical ripening, mechanical ripening with a Foley catheter is more effective than prostaglandin preparations.

METHODS

This was a retrospective analysis of multiparous women with a singleton gestation who required cervical ripening in a single tertiary center from 2014 to 2019. Women who underwent cervical ripening with a Foley catheter (Foley group) were compared with women who underwent cervical ripening using a controlled-release dinoprostone vaginal insert (PGE₂-CR group) or dinoprostone vaginal gel (PGE₂-gel group). The primary outcome was the ripening-to-delivery interval.

RESULTS

A total of 229 women met the study criteria (Foley group: 95; PGE₂-CR group: 83; PGE₂-gel group: 51). Women in the Foley group had a significantly shorter ripening-to-delivery interval compared with women in the PGE₂-CR group (16.2 ± 9.2 hours vs. 27.0 ± 14.8 hours; P < 0.001) and were more likely to deliver within 12 hours (47.4% vs. 12.0%; P < 0.001; adjusted relative risk [aRR] 3.87; 95% confidence interval [CI] 2.07-7.26) and within 24 hours (78.9% vs. 49.4%; P < 0.001; aRR 1.61; 95% CI 1.26-2.06). Women in the Foley group were also less likely to require a second ripening method compared with women in the PGE₂-CR group (1.1% vs. 8.4%; P = 0.018; aRR 7.26; 95% CI 2.99-17.62). These differences were not observed when comparing the Foley and the PGE₂-gel groups. The cesarean section rate was similar among the Foley group (9.5%), PGE₂-CR group (9.6%; P = 0.970), and PGE₂-gel group (11.8%; P = 0.664).

CONCLUSION

In multiparous women requiring cervical ripening, all methods of cervical ripening have a similar success rate. However, the use of a PGE₂-CR insert is associated with a considerably longer interval to delivery compared with a Foley catheter or PGE₂ gel.

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.

Planned cesarean or vaginal delivery for women in spontaneous labor with a twin pregnancy: A secondary analysis of the Twin Birth Study

BACKGROUND

The Twin Birth Study, a multicenter randomized controlled trial, found no differences in neonatal outcomes in women with twins randomized to planned cesarean or vaginal delivery. Nevertheless, women who present in spontaneous labor might expect a better outcome following a trial of vaginal delivery than undergoing cesarean delivery. In this secondary analysis, we aimed to compare neonatal outcomes of women who presented in spontaneous labor in the two arms of the Twin Birth Study.

METHODS

Women in whom the first twin was in the cephalic presentation were randomized between 32 + 0 and 38 + 6 weeks to planned vaginal delivery or cesarean. The primary outcome was a composite of fetal or neonatal death or serious neonatal morbidity.

RESULTS

Of the 2804 women included in the Twin Birth Study, 823 women in the planned vaginal delivery arm and 612 in the planned cesarean arm presented in spontaneous labor. Although the odds ratio favored planned vaginal delivery, there was no statistically significant difference in the rate of primary outcome between the vaginal delivery and cesarean arms (1.8% vs 2.7%, respectively; P = 0.16; OR 1.49; 95% CI, 0.87-2.55). Similarly, the rates of the individual components of the primary outcome and of maternal adverse outcome were similar between the two arms.

CONCLUSION

In women with twins who present in spontaneous labor between 32 + 0 and 38 + 6 weeks' gestation, where the first twin is cephalic, a policy of planned vaginal delivery or cesarean is not associated with significant differences in neonatal or maternal outcomes.

The Effect of Birth Order on Neonatal Morbidity and Mortality in Very Preterm Twins

Objective  This retrospective cohort study examined the effect of birth order on neonatal morbidity and mortality in very preterm twins. Study Design Using 2005 to 2012 data from the Canadian Neonatal Network, very preterm twins born between 24 ^0/7 and 32 ^6/7 weeks of gestation were included. Odds of morbidity and mortality of second-born cotwins compared with first-born cotwins were examined by matched-pair analysis. Outcomes were neonatal death, severe brain injury (intraventricular hemorrhage grade 3 or 4 or persistent periventricular echogenicity), bronchopulmonary dysplasia, severe retinopathy of prematurity (ROP) (> stage 2), necrotizing enterocolitis (≥ stage 2), and respiratory distress syndrome (RDS). Multivariable analysis was performed adjusting for confounders. Result There were 6,636 twins (3,318 pairs) included with a mean gestational age (GA) of 28.9 weeks. A higher rate of small for GA occurred in second-born twins (10 vs. 6%). Mortality was significantly lower for second-born twins (4.3 vs. 5.3%; adjusted odds ratio: 0.75; 95% confidence interval [CI]: 0.59-0.95). RDS (66 vs. 60%; adjusted odds ratio: 1.40; 95% CI: 1.29-1.52) and severe retinopathy (9 vs. 7%; adjusted odds ratio: 1.46; 95% CI: 1.07-2.01) were significantly higher in second-born twins. Conclusion Thus, while second-born twins had reduced odds of mortality, they also had increased odds of RDS and ROP.

The effect of induction method in twin pregnancies: a secondary analysis for the twin birth study

Background

This secondary analysis for the Twin Birth Study, an international, multicenter trial, aimed to compare the cesarean section rates and safety between methods of induction of labor in twin pregnancies.

Methods

Women with twin pregnancies where the first twin was in a cephalic presentation and who presented for labor induction, were non-randomly assigned to receive prostaglandin or amniotomy and/or oxytocin. Main outcome measures were the rates of unplanned cesarean section and neonatal and maternal mortality or serious morbidity.

Results

153 (41.5%) were induced by prostaglandin (prostaglandin group) and 215 (58.5%) were induced by amniotomy and/or oxytocin alone (no prostaglandin group). Induction using prostaglandin was more common in countries with a low perinatal mortality rate <10/1000 (45.7 versus 32.5%, p = 0.02). Cesarean section rates were similar in the two groups: 62/153 (40.5%) in the prostaglandin group and 87/215 (40.5%) in the no prostaglandin group (odds ratio 1, 95% CI 0.65-1.5). Nulliparity, late maternal age, non-cephalic presentation of twin B and high country’s perinatal mortality rate were found to be independently associated with the induction to end with an unplanned cesarean section. There were no significant differences between groups with respect to maternal or neonatal adverse outcomes.

Conclusions

The need for cervical ripening by prostaglandin had no effect on the incidence of cesarean delivery or an abnormal outcome. There is a significant risk of unplanned cesarean section independent of chosen induction method.

Trial registration

This trial was registered at the International Standard Randomized Controlled Trial Register (identifier ISRCTN74420086; December 9, 2003) and retrospectively registered at the www.clinicaltrials.gov (identifier NCT 00187369; September 12, 2005).

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-1201-8) contains supplementary material, which is available to authorized users.