Placental complications in subsequent pregnancies after prior cesarean section performed in the first versus second stage of labor

Cesarean section at full dilatation in the first birth is not associated with an increased risk of subsequent miscarriage: A historical cohort study

INTRODUCTION

Cesarean section at full dilatation has been associated with an increased risk of subsequent preterm birth. We hypothesized that there may be an increased risk of miscarriage in pregnancies that follow cesarean section at full dilatation. This study aimed to determine if a first-term (≥37 weeks) cesarean section at full dilatation is associated with an increased risk of miscarriage in the next pregnancy.

MATERIAL AND METHODS

A historical cohort study was conducted using routinely collected hospital data within the Aberdeen Maternity and Neonatal Databank (AMND). The population included were women who had a first-term birth and who had a second birth recorded within the AMND. Logistic and multinomial regression was used to determine any association with miscarriage at any gestation and for early (<13 weeks gestation) and late (13-23 + 6 weeks gestation) miscarriage, with cesarean section at full dilatation defined as the exposure. Miscarriage in the second pregnancy (spontaneous loss of intrauterine pregnancy prior to 24 weeks gestation) was the primary outcome.

RESULTS

In total, 33 452 women were included. Women who had a first cesarean section at full dilatation were no more likely to have a miscarriage at any gestation than women with all other modes of first birth (including all vaginal births, planned CS, and the first stage of labor (<10 cm dilated CS)) [adjusted OR 0.84 (0.66-1.08); p = 0.18]. There was no association with early or late miscarriage after a CSfd, though the sample size for late miscarriage was small.

CONCLUSIONS

This is the first observational study to investigate the risk of miscarriage following first-term CSfd. We found no association between miscarriage at any gestation following a first-term CSfd compared to all other modes of first birth.

Engaging women to set the research agenda for assisted vaginal birth

INTRODUCTION

Public and patient involvement can provide crucial insights to optimise research by enhancing relevance and appropriateness of studies. The World Health Organization (WHO) engaged in an inclusive process to ensure that both technical experts and women had a voice in defining the research gaps and needs to increase or reintroduce the use of assisted vaginal birth (AVB) in settings where this intervention is needed but unavailable or underused.

METHODS

We describe the methods and outcomes of online workshops led by WHO to obtain women representatives' perspectives about AVB research gaps and needs.

RESULTS

After technical experts created a list of research questions based on various evidence syntheses, WHO organised four online workshops with 31 women's representatives from 27 mostly low- and middle-income (LMIC) countries. Women rated the importance and priority of the research questions proposed by the technical experts, improving and broadening some of them, added new questions, and voiced their main concerns and views about AVB. Women helped to put the research questions into context in their communities, highlighted neglected factors/dimensions that influence practices and affect women's experience during labour and childbirth, underscored less salient consequences of AVB, and highlighted the main concerns of women about research on AVB. The consolidated vision of technical experts and women's representatives resulted in a technical brief published by WHO. The technical brief is expected to stimulate global research and action closely aligned with women's priorities.

CONCLUSIONS

We describe a successful experience of engaging women, mostly from LMICs, in the identification of research gaps and needs to reintroduce AVB use. This process contributed to better aligning research questions with women's views, concerns, and priorities. Given the scarcity of reports about engaging women from LMICs to optimise research, this successful experience can serve as an inspiration for future work.

PATIENT OR PUBLIC CONTRIBUTION

Women representatives were involved at every stage of the workshops described in full in this manuscript.

Operative delivery in the second stage of labor and preterm birth in a subsequent pregnancy: a systematic review and meta-analysis

OBJECTIVE

This study aimed to quantify the association between mode of operative delivery in the second stage of labor (cesarean delivery vs operative vaginal delivery) and spontaneous preterm birth in a subsequent pregnancy.

DATA SOURCES

MEDLINE, Embase, EmCare, CINAHL, the Cochrane Library, Web of Science: Core Collection, and Scopus were searched from database inception to April 1, 2023.

STUDY ELIGIBILITY CRITERIA

All retrospective cohort studies with participants who had a second-stage cesarean delivery (defined as intrapartum cesarean delivery at full cervical dilation) or operative vaginal delivery (including forceps- and/or vacuum-assisted delivery) and that reported the rate of preterm birth (either spontaneous or not specified) in subsequent pregnancy were included.

METHODS

Both a descriptive analysis and a meta-analysis were performed. A meta-analysis was performed for dichotomous data using the Mantel-Haenszel random-effects model and used the odds ratio as an effect measure with 95% confidence intervals. The risk of bias was assessed using Cochrane's 2022 Risk Of Bias In Non-randomized Studies of Exposure tool.

RESULTS

After screening 2671 articles from 7 databases, a total of 18 retrospective cohort studies encompassing 605,138 patients were included. The pooled rates of spontaneous preterm birth in a subsequent pregnancy were 6.9% (12 studies) after second-stage cesarean delivery and 2.6% (8 studies) after operative vaginal delivery. A total of 7 studies encompassing 75,460 patients compared the primary outcome of spontaneous preterm birth after second-stage cesarean delivery vs operative vaginal delivery in an index pregnancy with an odds ratio of 2.01 (95% confidence interval, 1.57-2.58) in favor of operative vaginal delivery. However, most studies did not include important confounding factors, did not address exposure misclassification because of failed operative vaginal delivery, and considered operative vaginal delivery as a homogeneous category with no distinction between forceps- and vacuum-assisted deliveries.

CONCLUSION

Although a synthesis of the existing literature suggests that the risk of spontaneous preterm birth is higher in those with a previous second-stage cesarean delivery than in those with operative vaginal delivery, the risk of bias in these studies is very high. Findings should be interpreted with caution.