Pregnancy Outcome and Mode of Delivery After a Previous Operative Vaginal Delivery

Interpregnancy interval after vacuum delivery and subsequent perinatal outcomes

OBJECTIVE

To evaluate whether a short interpregnancy interval (IPI) after vacuum extraction (VE), poses similar perinatal risks in a subsequent pregnancy.

METHODS

This was a retrospective, single-center cohort study between 2011 and 2021. Nulliparous women with term, singleton VE deliveries and with known pregnancy outcomes in their subsequent pregnancy were eligible for inclusion in the study. Each woman was allocated into one of two groups based on the IPI, <18 months and between 18 and 60 months. The primary outcome was the risk of spontaneous preterm birth (PTB) <37 weeks in the consecutive birth.

RESULTS

We included 1094 pregnancies: 212 (19.4%) with IPI <18 months and 882 (80.6%) with IPI between 18 and 60 months following the previous VE delivery. The VE characteristics were comparable between the groups. Young maternal age was a risk factor for a short IPI (28.0 ± 4.8 vs 30.3 ± 4 years, P < 0.01). Spontaneous PTB <37 weeks was significantly higher in the IPI <18 months group with 18-60 months (7.1% vs 2.6%, P = 0.002). Polynomial regression analysis also confirmed a significantly increased risk of preterm birth <37 weeks (P < 0.01). Short IPI <18 months was also associated with an increase in the risk of low birthweight <2500 g (6.1% vs 2.8%, P = 0.02) and admission to the neonatal intensive care unit (6.1% vs 2.6%, P = 0.013). The incidence of recurrent VE, albeit significant (2.3% vs 4.9%, P = 0.049), was low in both groups. No differences were noted in any of the other secondary outcomes.

CONCLUSION

Short IPI (<18 months) following term VE delivery is associated with higher neonatal risks, particularly PTB, in the subsequent pregnancy. These findings are particularly important when counseling women planning an optimal IPI.

Projecting future prolapse outcomes with induction of labor at 39 weeks: a decision analysis

INTRODUCTION AND HYPOTHESIS

In 2018, the ARRIVE trial (A Randomized Trial of Induction Versus Expectant Management) concluded that routine induction of labor (IOL) at 39 weeks gestation decreases cesarean delivery risk, with slightly lighter birthweight infants. We debated whether routine IOL would improve, worsen, or not change POP risk compared with expectant management (EM).

METHODS

We constructed a decision analysis model with a lifetime horizon where nulliparous women reaching 39 weeks underwent IOL or EM. Subsequent vaginal versus cesarean delivery varied based on prior deliveries for up to four births. Subsequent delivery prior to 39 weeks and distribution of gestational age, birthweight, and delivery mode between 24 and 39 weeks was modeled from national data. We modeled increased POP risk with increasing vaginal parity, forceps delivery, and weight of largest infant delivered vaginally, accounting for differential infant weights in each strategy.

RESULTS

IOL and EM have similar population-wide POP risk (15.9% and 15.7% respectively). Among women with only spontaneous vaginal deliveries that reached 39 weeks or beyond, the prevalence of POP was 20% after one delivery and 29% after four deliveries, with no difference between groups. The cesarean rate was lower with IOL (27.8% versus 29.8%). Sensitivity analysis revealed no meaningful thresholds among the variables, supporting model robustness.

CONCLUSION

While routine induction of labor at 39 weeks results in a meaningfully higher vaginal delivery rate, there was no increase in POP, possibly due to the protective effect of lower birthweight.

Birthweight difference between deliveries and the risk of obstetric anal sphincter injury in parous women

INTRODUCTION AND HYPOTHESIS

While obstetric anal sphincter injury (OASI) is less frequent in parous compared to nulliparous women, it remains a major concern affecting quality of life of women worldwide. The aim of this study was to evaluate the association between birthweight (BW) difference between deliveries and risk of OASI in parous women.

METHODS

We performed a retrospective case-control study including parous women with at least one previous vaginal delivery who were diagnosed with OASI. The control group consisted of parous women who did not have OASI during vaginal delivery. Controls were matched in a 1:2 ratio by year of birth, maternal age, and parity. Medical history, obstetric background, and current labor-related data were compared. Further univariate and multivariable analyses were performed, assessing for risk factors for OASI.

RESULTS

One hundred eight parous women who had a diagnosis of OASI and a control group of 216 parturients who delivered without OASI were included in the final analysis. Differences between the current BW and the preceding and maximal previous BW were evaluated. There were significantly higher rates of women who had a larger neonate with > 500 g difference between the current and previous BW in the OASI group than in those with no OASI (28.7% vs. 12.30%, respectively; p < 0.001). Following a multivariable analysis for the dependent parameter of OASI, the following parameters were found to be independently associated with OASI outcome: previous operative vaginal delivery, BW ≥ 90th percentile, and current BW ≥ 500 g compared to previous maximal BW.

CONCLUSIONS

In parous women, neonatal BW increase between deliveries of > 500 g is associated with OASI.

Outcomes of attempted vaginal births after previous recurrent operative vaginal deliveries: An individual cumulative risk analysis

BACKGROUND

Data about the risk of recurrence of vacuum extraction (VE) in multiple consecutive deliveries are scarce. We aimed to evaluate the pattern and individual cumulative risk of recurrence of VE in consecutive term deliveries.

STUDY DESIGN

A retrospective cohort study based on a validated electronic database at a single center between 2005 and 2019. For the purpose of the study, we focused on consecutive term deliveries of all primiparas (P1) that had a record of at least one additional delivery during the study period. We identified P1 VE deliveries (reference group) and calculated the individual cumulative risk of repeated VE for three consecutive deliveries. Multivariate analysis was conducted adjusting for potential confounders.

RESULTS

We identified 35 113 primiparas that met inclusion criteria. The overall VE rate for P1 was 17.9% (6969 parturient). The cumulative rates of repeated VEs at the 2nd, 3rd, and 4th deliveries were 8.6%, 26.8%, and 25.0%, respectively. The risk of recurrent VE for each of the consecutive deliveries was confirmed after adjustment for confounders (aOR [95% CI]: 5.8 [4.76-7.04], 34.2 [18.59-62.81], and 113.9 [9.77-1328.69] for the 2nd, 3rd, and 4th consecutive deliveries, respectively).

CONCLUSION

Women with VE at the first and second deliveries have a substantially increased risk of VE in their following deliveries; this finding may influence woman's preference when choosing future mode of delivery.

Are freestanding midwifery units a safe alternative to obstetric units for low-risk, primiparous childbirth? An analysis of effect differences by parity in a matched cohort study

Background

Intrapartum complications and the use of obstetric interventions are more common in primiparous childbirth than in multiparous childbirth, leading to concern about out of hospital birth for primiparous women. The purpose of this study was to determine whether the effect of birthplace on perinatal and maternal morbidity and the use of obstetric interventions differed by parity among low-risk women intending to give birth in a freestanding midwifery unit or in an obstetric unit in the North Denmark Region.

Methods

The study is a secondary analysis of data from a matched cohort study including 839 low-risk women intending birth in a freestanding midwifery unit (primary participants) and 839 low-risk women intending birth in an obstetric unit (individually matched control group). Analysis was by intention-to-treat. Conditional logistic regression analysis was applied to compute odds ratios and effect ratios with 95% confidence intervals for matched pairs stratified by parity.

Results

On no outcome did the effect of birthplace differ significantly between primiparous and multiparous women. Compared with their counterparts intending birth in an obstetric unit, both primiparous and multiparous women intending birth in a freestanding midwifery unit were significantly more likely to have an uncomplicated, spontaneous birth with good outcomes for mother and infant and less likely to require caesarean section, instrumental delivery, augmented labour or epidural analgesia (although for caesarean section this trend did not attain statistical significance for multiparous women). Perinatal outcomes were comparable between the two birth settings irrespective of parity. Compared to multiparas, transfer rates were substantially higher for primiparas, but fell over time while rates for multiparas remained stable.

Conclusions

Freestanding midwifery units appear to confer significant advantages over obstetric units to both primiparous and multiparous mothers, while their infants are equally safe in both settings. Our findings thus support the provision of care in freestanding midwifery units as an alternative to care in obstetric units for all low-risk women regardless of parity. In view of the global rise in caesarean section rates, we consider it an important finding that freestanding midwifery units show potential for reducing first-birth caesarean.

Electronic supplementary material

The online version of this article (doi:10.1186/s12884-016-1208-1) contains supplementary material, which is available to authorized users.

Oxytocin augmentation of labour in women with epidural analgesia for reducing operative deliveries

BACKGROUND

The rate of operative deliveries (both caesarean sections, vacuum extractions and forceps), continues to rise throughout the world. These are associated with significant maternal and neonatal morbidity. The most common reasons for operative births in nulliparous women are labour dystocia (failure to progress), and non-reassuring fetal status. Epidural analgesia has been shown to slow the progress of labour, as well as increase the rate of instrumental deliveries. However, it is unclear whether the use of oxytocin in women with epidural analgesia results in a reduction in operative deliveries, and thereby reduces both maternal and fetal morbidity.

OBJECTIVES

To determine whether augmentation of women using epidural analgesia with oxytocin will decrease the incidence of operative deliveries and thereby reduce fetal and maternal morbidity.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 June 2013).

SELECTION CRITERIA

All published and unpublished randomised and quasi-randomised trials that compared augmentation with oxytocin of women in spontaneous labour with epidural analgesia versus intent to manage expectantly were included. Cluster-randomised trials were eligible for inclusion but none were identified.Cross-over study designs were unlikely to be relevant for this intervention, and we planned to exclude them if any were identified. We did not include results that were only available in published abstracts.

DATA COLLECTION AND ANALYSIS

The two review authors independently assessed for inclusion the 16 studies identified as a result of the search strategy. Both review authors independently assessed the risk of bias for each included study. Both review authors independently extracted data. Data were checked for accuracy.

MAIN RESULTS

We included two studies, involving 319 women. There was no statistically significant difference between the two groups in either of the primary outcomes of caesarean section (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.42 to 2.12) or instrumental delivery (RR 0.88, 95% CI 0.72 to 1.08). Similarly, there were no statistically significant differences between the two groups in any of the secondary outcomes for which data were available. This included Apgar score less than seven at five minutes (RR 3.06, 0.13 to 73.33), admission to neonatal intensive care unit (RR 1.07, 95% CI 0.29 to 3.93), uterine hyperstimulation (RR 1.32, 95% CI 0.97 to 1.80) and postpartum haemorrhage (RR 0.96, 95% CI 0.58, 1.59).

AUTHORS' CONCLUSIONS

There was no statistically significant difference identified between women in spontaneous labour with epidural analgesia who were augmented with oxytocin, compared with those who received placebo. However, due to the limited number of women included in the studies, further research in the form of randomised controlled trials are required.

Characteristics in the first vaginal birth and their association with mode of delivery in the subsequent birth

BACKGROUND

The extent to which complications or adverse outcomes in a first vaginal birth may contribute to mode of delivery in the next birth remains unclear. This study examines the impact of the first birth on subsequent mode of delivery.

METHODS

The study population included women with a first vaginal birth and a consecutive second birth. Data were obtained from linked birth and hospital records for the state of New South Wales, Australia 2000-09. The primary outcome was the mode of delivery for the second birth. Planned caesarean was modelled using logistic regression; intrapartum caesarean and instrumental delivery were modelled using multinomial logistic regression.

RESULTS

Of the 114 287 second births, 4.2% were planned caesarean, 3.0% were intrapartum caesarean and 4.8% were instrumental deliveries. Adjusted risk factors from the first birth for a planned second birth caesarean were third to fourth degree tear [odds ratio (OR) = 5.0 [95% confidence interval (CI) 4.6, 5.4]], severe neonatal morbidity (OR = 3.2 [95% CI 2.9, 3.6]), perinatal death (OR = 3.2 [95% CI 2.3, 4.4]), severe maternal morbidity (OR = 2.8 [95% CI 2.3, 3.3]), instrumental delivery, large infant, labour induction, epidural use, use of oxytocin for augmentation and episiotomy. Important risk factors (OR > 2) for intrapartum caesarean in the second birth were perinatal death or severe neonatal morbidity in the first birth. Risk factors for instrumental delivery in the second birth were perinatal death, preterm delivery and instrumental delivery.

CONCLUSIONS

Obstetrical interventions and adverse pregnancy outcomes in the first birth were associated with increased risk of operative delivery in the second birth.

Oxytocin augmentation of labour in women with epidural analgesia for reducing operative deliveries

BACKGROUND

The rate of operative deliveries (both caesarean sections, vacuum extractions and forceps), continues to rise throughout the world. These are associated with significant maternal and neonatal morbidity. The most common reasons for operative births in nulliparous women are labour dystocia (failure to progress), and non-reassuring fetal status. Epidural analgesia has been shown to slow the progress of labour, as well as increase the rate of instrumental deliveries. However, it is unclear whether the use of oxytocin in women with epidural analgesia results in a reduction in operative deliveries, and thereby reduces both maternal and fetal morbidity.

OBJECTIVES

To determine whether augmentation of women using epidural analgesia with oxytocin will decrease the incidence of operative deliveries and thereby reduce fetal and maternal morbidity.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (29 February 2012).

SELECTION CRITERIA

All published and unpublished randomised and quasi-randomised trials that compared augmentation with oxytocin of women in spontaneous labour with epidural analgesia versus intent to manage expectantly were included. Cluster-randomised trials were eligible for inclusion but none were identified.Cross-over study designs were unlikely to be relevant for this intervention, and we planned to exclude them if any were identified. We did not include results that were only available in published abstracts.

DATA COLLECTION AND ANALYSIS

The two review authors independently assessed for inclusion the 16 studies identified as a result of the search strategy. Both review authors independently assessed the risk of bias for each included study. Both review authors independently extracted data. Data were checked for accuracy.

MAIN RESULTS

We included two studies, involving 319 women. There was no statistically significant difference between the two groups in either of the primary outcomes of caesarean section (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.42 to 2.12) or instrumental delivery (RR 0.88, 95% CI 0.72 to 1.08). Similarly, there were no statistically significant differences between the two groups in any of the secondary outcomes for which data were available. This included Apgar score less than seven at five minutes (RR 3.06, 0.13 to 73.33), admission to neonatal intensive care unit (RR 1.07, 95% CI 0.29 to 3.93), uterine hyperstimulation (RR 1.32, 95% CI 0.97 to 1.80) and postpartum haemorrhage (RR 0.96, 95% CI 0.58, 1.59).

AUTHORS' CONCLUSIONS

There was no statistically significant difference identified between women in spontaneous labour with epidural analgesia who were augmented with oxytocin, compared with those who received placebo. However, due to the limited number of women included in the studies, further research in the form of randomised controlled trials are required.