The association between fetal head position prior to vacuum extraction and pregnancy outcome

Precision of vacuum cup placement and its association with subgaleal hemorrhage and associated morbidity in term neonates

PURPOSE

To evaluate whether the precision of vacuum cup placement is associated with failed vacuum extraction(VE), neonatal subgaleal hemorrhage(SGH) and other VE-related birth trauma.

METHODS

All women with singleton term cephalic fetuses with attempted VE were recruited over a period of 30 months. Neonates were examined immediately after birth and the position of the chignon documented to decide whether the cup position was flexing median or suboptimal. Vigilant neonatal surveillance was performed to look for VE-related trauma, including subgaleal/subdural hemorrhages, skull fractures, scalp lacerations. CT scans of the brain were ordered liberally as clinically indicated.

RESULTS

The VE rate was 5.89% in the study period. There were 17(4.9%) failures among 345 attempted VEs. Thirty babies suffered from subgaleal/subdural hemorrhages, skull fractures, scalp lacerations or a combination of these, giving an incidence of VE-related birth trauma of 8.7%. Suboptimal cup positions occurred in 31.6%. Logistic regression analysis showed that failed VE was associated with a non-occipital anterior fetal head position (OR 3.5, 95% CI 1.22-10.2), suboptimal vacuum cup placement (OR 4.13, 95% CI 1.38-12.2) and a longer duration of traction (OR 8.79, 95% CI 2.13-36.2); while, VE-related birth trauma was associated with failed VE (OR 3.93, 95% CI 1.08-14.3) and more pulls (OR 4.07, 95% CI 1.98-8.36).

CONCLUSION

Suboptimal vacuum cup positions were related to failed VE but not to SGH and other vacuum-related birth trauma. While optimal flexed median cup positions should be most desirable mechanically to effect delivery, such a position does not guarantee prevention of SGH.

Maternal postures for fetal malposition in late pregnancy for improving the health of mothers and their infants

BACKGROUND

The optimal relationship of the fetus to the mother's birth canal is when the fetus is in the longitudinal lie, cephalic presentation with well-flexed head (vertex presentation), and in the occipito-anterior position. Fetal malposition is described as occipito-posterior (OP) when the back of the fetal head lies posteriorly in the mother's pelvis, and occipito-transverse (OT) when the back of the fetal head lies transversely in the mother's pelvis. The fetal head will often be deflexed and may extend further to a mento-anterior or mento-transverse position, where the chin is anterior or transverse to the maternal pelvis. Fetal malposition is associated with both maternal and fetal complications, including prolonged labour, fetal distress, maternal exhaustion, need for caesarean section, operative vaginal birth, and increased risk of perineal trauma and anal sphincter injuries. This review considered positional interventions in late pregnancy to correct fetal malposition. A separate Cochrane review addresses maternal postural position for fetal malposition during labour.

OBJECTIVES

To assess the effects of maternal posture for fetal malposition in women in late pregnancy.

SEARCH METHODS

We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (24 October 2022), and reference lists of retrieved studies.

SELECTION CRITERIA

Our selection criteria were randomised controlled trials and cluster-randomised controlled trials that included women in late pregnancy with a malposition of the fetus including OP and OT, mento-anterior and mento-transverse, or with uncertain fetal position, randomly allocated to use of specified maternal positioning in late pregnancy, compared with usual care.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed potential studies for inclusion in the review. We used standardised methodology for assessment of risk of bias and trustworthiness developed by the Cochrane Pregnancy and Childbirth Group.

MAIN RESULTS

We reviewed three full-text reports; we excluded one due to lack of a comparison group and listed two as awaiting classification. We needed further information from the report authors for both potentially suitable studies to account for substantial imbalances between the numbers allocated to each group in one, or identical numbers for all groups in the other. The failure to resolve these issues may have been due to the long interval since publication of the studies (2004 and 1983).

AUTHORS' CONCLUSIONS

We did not identify evidence for guiding practice with respect to positional interventions for fetal malposition in late pregnancy. More studies are needed to understand the effect of positional interventions in late pregnancy. Future research on positional interventions for fetal malposition in late pregnancy should include follow-up to determine whether short-term correction of fetal position translates to improved pregnancy outcomes. This might include interventions commenced in late pregnancy and repeated as needed until the onset of labour. The latter would be included in the review on maternal positions during labour.

Head position and vacuum-assisted delivery using the Kiwi Omnicup

OBJECTIVE

To evaluate the association between fetal head position during prevacuum assessment and adverse outcomes.

METHOD

This retrospective cohort study included all vacuum-assisted deliveries using the Kiwi Omnicup over 5 years. Primary outcomes were third- or fourth-degree perineal tear, pH < 7.1, and subgaleal hematoma (SGH). AGAR, neonatal intensive care unit admission, cephalohematoma, Erb's palsy, third-stage duration, and postpartum hemorrhage were secondary. Outcomes were compared between the occiput posterior (OP) and occiput anterior (OA) positions.

RESULTS

The study included 1960 patients. OP position was more likely to involve epidural analgesia (311 [82.5%] vs. 1216 [77%], P = 0.020), higher fetal head station (P = 0.001), higher percentage of cup detachments (121 cases [32.1%] vs. 307 [19.4%], P = 0.001), and longer procedure (5.5 ± 3.7 min vs. 4.7 ± 2.8 min, P = 0.001). OP was associated with umbilical cord pH < 7.1 (21 [5.5%] vs. 52 [3.9%], P = 0.032), NICU admissions (16 [4.2%] vs. 38 [2.4%], P = 0.049), SGH (18 [4.8%] vs. 38 [2.4%], P = 0.013), and high-degree perineal tears (12 [3.2%] vs. 26 [1.7%], with borderline significance, P = 0.051). SGH and high-grade tears remained significantly associated with OP position (P = 0.008 and P = 0.016, respectively) after adjusting for maternal age, nulliparity, diabetes, epidural anesthesia, preprocedure head station, and birth weight.

CONCLUSION

OP position is an independent risk-factor for anal sphincter injury and SGH during vacuum-assisted delivery.

Fetal malposition in labour and health outcomes for women and their newborn infants: A retrospective cohort study

INTRODUCTION

Occiput-posterior (OP) or occiput-transverse (OT) fetal malposition has a prevalence of 33-58% in the first-stage of labour with 12-22% persisting until delivery. Malposition is associated with significant maternal and neonatal morbidity. Most previous studies report the incidence and adverse maternal and fetal outcomes of persistent fetal malposition in the second stage of labour and do not include outcomes that may be present in the first stage of labour.

AIMS

To assess the incidence and health outcomes for women and their newborn infants of a fetal malposition in the first or second stage of labour.

MATERIALS AND METHODS

A retrospective cohort study of 738 maternity records (randomly selected) from a tertiary hospital in New Zealand. Maternal and neonatal characteristics are described. Outcomes for women with a fetus in an OP or OT position in labour are compared to those for women with a fetus in an occiput-anterior position (OA).

RESULTS

499 (68%) women had an OP/OT positioned fetus and 239 (32%) had an OA positioned fetus on vaginal examination in labour. Women had similar characteristics except a body mass index ≥30 kg/m2 was more common in the OP/OT group. Fetal malposition appears to be more likely in women with a right-sided fetal occiput. Three quarters of OP/OT fetuses rotated anteriorly by birth. Fetal malposition compared to no malposition was associated with oxytocin augmentation, epidural use, a longer first stage of labour, fewer normal vaginal births, and more caesarean sections. Fetal malposition during labour was not associated with adverse neonatal outcomes.

CONCLUSION

Interventions such as maternal posture in the first and second stage of labour could potentially reduce the incidence of malposition and improve health outcomes for mothers.

Maternal postures for fetal malposition in labour for improving the health of mothers and their infants

BACKGROUND

Fetal malposition (occipito-posterior and persistent occipito-transverse) in labour is associated with adverse maternal and infant outcomes. Whether use of maternal postures can improve these outcomes is unclear. This Cochrane Review of maternal posture in labour is one of two new reviews replacing a 2007 review of maternal postures in pregnancy and labour.

OBJECTIVES

To assess the effect of specified maternal postures for women with fetal malposition in labour on maternal and infant morbidity compared to other postures.  SEARCH METHODS: We searched Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (13 July 2021), and reference lists of retrieved studies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or cluster-RCTs conducted among labouring women with a fetal malposition confirmed by ultrasound or clinical examination, comparing a specified maternal posture with another posture. Quasi-RCTs and cross-over trials were not eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion, risk of bias, and performed data extraction. We used mean difference (MD) for continuous variables, and risk ratios (RRs) for dichotomous variables, with 95% confidence intervals (CIs). We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included eight eligible studies with 1766 women.  All studies reported some form of random sequence generation but were at high risk of performance bias due to lack of blinding. There was a high risk of selection bias in one study, detection bias in two studies, attrition bias in two studies, and reporting bias in two studies. Hands and knees The use of hands and knees posture may have little to no effect on operative birth (average RR 1.14, 95% CI 0.87 to 1.50; 3 trials, 721 women; low-certainty evidence) and caesarean section (RR 1.34, 95% CI 0.96 to 1.87; 3 trials, 721 women; low-certainty evidence) but the evidence is uncertain; and very uncertain for epidural use (average RR 0.74, 95% CI 0.41 to 1.31; 2 trials, 282 women; very low-certainty evidence), instrumental vaginal birth (average RR 1.04, 95% CI 0.57 to 1.90; 3 trials, 721 women; very low-certainty evidence), severe perineal tears (average RR 0.88, 95% CI 0.03 to 22.30; 2 trials, 586 women; very low-certainty evidence), maternal satisfaction (average RR 1.02, 95% CI 0.68 to 1.54; 3 trials, 350 women; very low-certainty evidence), and Apgar scores less than seven at five minutes (RR 0.71, 95% CI 0.21 to 2.34; 2 trials, 586 babies; very low-certainty evidence).  No data were reported for the hands and knees comparisons for postpartum haemorrhage, serious neonatal morbidity, death (stillbirth or death of liveborn infant), admission to neonatal intensive care, neonatal encephalopathy, need for respiratory support, and neonatal jaundice requiring phototherapy.  Lateral postures The use of lateral postures may have little to no effect on reducing operative birth (average RR 0.72, 95% CI 0.43 to 1.19; 4 trials, 871 women; low-certainty evidence), caesarean section (average RR 0.78, 95% CI 0.44 to 1.39; 4 trials, 871 women; low-certainty evidence), instrumental vaginal birth (average RR 0.73, 95% CI 0.39 to 1.36; 4 trials, 871 women; low-certainty evidence), and maternal satisfaction (RR 0.96, 95% CI 0.84 to 1.09; 2 trials, 451 women; low-certainty evidence), but the evidence is uncertain. The evidence is very uncertain about the effect of lateral postures on severe perineal tears (RR 0.66, 95% CI 0.17 to 2.48; 3 trials, 609 women; very low-certainty evidence), postpartum haemorrhage (RR 0.90, 95% CI 0.48 to 1.70; 1 trial, 322 women; very low-certainty evidence), serious neonatal morbidity (RR 1.41, 95% CI 0.64 to 3.12; 3 trials, 752 babies; very low-certainty evidence), Apgar scores less than seven at five minutes (RR 0.25, 95% CI 0.03 to 2.24; 1 trial, 322 babies; very low-certainty evidence), admissions to neonatal intensive care (RR 1.41, 95% CI 0.64 to 3.12; 2 trials, 542 babies; very low-certainty evidence) and neonatal death (stillbirth or death of liveborn) (1 trial, 210 women and their babies; no events).  For the lateral posture comparisons, no data were reported for epidural use, neonatal encephalopathy, need for respiratory support, and neonatal jaundice requiring phototherapy. We were not able to estimate the outcome death (stillbirth or death of liveborn infant) due to no events (1 trial, 210 participants).  AUTHORS' CONCLUSIONS: We found low- and very low-certainty evidence which indicated that the use of hands and knees posture or lateral postures in women in labour with a fetal malposition may have little or no effect on health outcomes of the mother or her infant. If a woman finds the use of hands and knees or lateral postures in labour comfortable there is no reason why they should not choose to use them. Further research is needed on the use of hands and knees and lateral postures for women with a malposition in labour. Trials should include further assessment of semi-prone postures, same-side-as-fetus lateral postures with or without hip hyperflexion, or both, and consider interventions of longer duration or that involve the early second stage of labour.

Pregnant women's views on the acceptability, enablers, and barriers of participation in a randomized controlled trial of maternal posture for fetal malposition in labor

INTRODUCTION

Fetal malposition in labor results in adverse maternal and infant health. Whilst evidence for effective interventions is inconclusive, based on the hypothesis that gravity corrects malposition, the feasibility and design of a randomized controlled trial (RCT) to improve maternal and infant health outcomes should be considered. The aim was to assess pregnant women's views on the acceptability, enablers, and barriers of participation in an RCT of maternal posture for fetal malposition in labor.

METHODS

A web-based anonymous survey of pregnant women was conducted in Auckland during 2020. Quantitative data were summarized descriptively using a chi-squared test to assess differences in proportions. Maternal characteristics influence on women's responses was assessed using cross-tabulation. A thematic content analysis of free text responses was undertaken.

RESULTS

Most of the 206 respondents were aged 26-35 years (75%), 29-38 weeks pregnant (71%), of European (40%) or Asian (36%) ethnicity, and similarly nulliparous or multiparous. Most women (76%) knew of fetal malposition in labor; however, only 28% were aware of maternal posture to correct this. Most women (86%) were interested in labor research and although 37% would participate in an RCT, almost half (47%) were unsure and a 15% would not participate. Concerns mostly related to comfort (22%). Nearly half of women (49%) would need to consult their partner regarding participation in an RCT.

CONCLUSIONS

Enablers for participation in a posture trial in labor include measures to enhance maternal comfort, increasing awareness of malposition and the role of posture, and involving partners in pre-trial counselling and recruitment.

Adverse outcomes in vacuum-assisted delivery after detachment of non-metal cup: a retrospective cohort study

PURPOSE

To evaluate neonatal and maternal outcomes associated with detachment of non-metal vacuum cup during delivery and to identify risk factors for these detachments.

METHODS

This retrospective cohort study included women with singleton pregnancy, who underwent vacuum-assisted vaginal delivery with a non-metal vacuum cup in a single academic institution, January 2014-August 2019. Failed vacuum deliveries were excluded. Primary outcomes were defined as subgaleal hematoma (SGH) and cord blood pH < 7.15. Secondary outcome included other neonatal complications and adverse maternal outcomes. Outcomes were compared between vacuum-assisted deliveries with and without cup detachment during the procedure.

RESULTS

A total of 3246 women had successful VAD and met the inclusion criteria. During the procedure, the cup detached at least once in 665 (20.5%) deliveries and did not detach in 2581 (79.5%). The cup detachment group experienced higher rates of SGH (8.9% vs. 3.5%, p = 0.001) and cord blood pH < 7.15 (9.8% vs. 7.1%, p = 0.03). There were also more neonatal intensive care unit admissions (NICU) (4.4% vs. 2.7%, p = 0.03) and more fetuses with occiput posterior position (70.8% vs. 79.4%, p = 0.001), the vacuum duration was slightly longer (6 ± 3.7 vs. 5 ± 2.9 min) and more neonates had birth weights > 3700 g (14.1% vs, 10.3%, p = 0.006). Interestingly, there were more males in that group (60.6 vs. 54.6, p = 0.005). All these factors remained significant after controlling for potential confounders.

CONCLUSIONS

Vacuum cup detachment has several predictive characteristics and is associated with adverse neonatal outcomes that should be incorporated into decisions made during the procedure.

Pregnancy outcome after cesarean section following a failed vacuum attempt

OBJECTIVE

To compare the pregnancy outcome of women who underwent cesarean section in the second stage of labor, with or without a vacuum extraction attempt.

METHODS

A retrospective cohort study of women who underwent a cesarean section during the second stage of labor in a single tertiary university-affiliated medical center (2012-2019). Pregnancy outcome was compared for women who underwent cesarean section following a failed vacuum extraction to women who had cesarean section during the second stage of labor with no vacuum extraction attempt. Neonatal outcomes included umbilical artery pH less than 7.1, Apgar at 5 min < 7, hypoxemic ischemic encephalopathy and NICU admission. Maternal outcomes included duration of hospitalization, need for blood transfusion and need for re-surgery in 45 days.

RESULTS

Overall, 88,375 women delivered during the study period. Of them, 120 women had a cesarean section following a failed vacuum (study group). Another 551 women underwent a cesarean section in the second stage of labor without a VE attempt (control group). The groups were similar with regard to obstetrical and demographic characteristics. The rates of umbilical artery pH < 7.1 (17.50% vs 6.53%, p < .001), NICU admission (13.33% vs 2.90%, p < .001), hypoxemic ischemic encephalopathy (5.83% vs 0.18%, p < .001) and epicranial sub-aponeurotic hemorrhage (16.67% vs 2.18%, p < .001) were significantly higher in the study group. No significant differences were found in maternal outcomes. In a sub-analysis including only labor with reassuring fetal heart tracing, failed vacuum attempt was associated with higher rate of NICU admission and epicranial hemorrhage (16.67% vs 3.13%, p = .009, 27.78% vs. 3.41, p = .001, respectively).

CONCLUSION

Failed vacuum attempt is associated with a significant increased neonatal morbidity, but not increased maternal morbidity.

The role of mediolateral episiotomy during vacuum-assisted vaginal delivery with soft cup devices

PURPOSE

This study evaluated whether episiotomy during vacuum-assisted delivery leads to fewer third- and fourth-degree tears.

METHODS

This was a retrospective cohort study of all nulliparas who underwent a singleton, soft cup, vacuum-assisted vaginal delivery in one institution, from January 2014 to August 2019. Failed vacuum deliveries were excluded. Based on power analysis calculation, a sample size of 500 women in each group was sufficient to detect an advantage of episiotomy, if present. Primary outcome was third- or fourth-degree perineal tear. Secondary outcomes were other maternal complications, and low neonatal cord pH and Apgar scores. Outcomes were compared between women with and without episiotomy.

RESULTS

During the study period, 2370 nulliparas had a vacuum-assisted vaginal delivery using soft vacuum cup and met the study inclusion criteria. Episiotomy was performed in 1868 (79%) women, and 502 (21%) delivered without episiotomy. Background characteristics were similar in both groups. There were no significant differences in the rates of third and fourth grade perineal lacerations between the two groups. Episiotomy was associated with higher rate of postpartum hemorrhage (p < 0.01) CONCLUSIONS: Using selective episiotomy for patients delivering vaginally with the assistance of soft cap vacuum does not increase third- or fourth-degree perineal tears.

Adverse neonatal and maternal outcome following vacuum-assisted vaginal delivery: does indication matter?

PURPOSE

To estimate the impact of indication for vacuum-assisted vaginal delivery on neonatal and maternal adverse outcome.

METHODS

Retrospective analysis of women carrying singleton-term pregnancies undergoing vacuum-assisted vaginal delivery in a tertiary hospital (2007-2014). Cohort was stratified by indication: non-reassuring fetal heart rate or prolonged second stage. Primary outcome was adverse neonatal outcome and secondary outcome was maternal morbidity. Logistic regression analysis was utilized to adjust for potential confounders.

RESULT

Overall, 4931 women met inclusion criteria. Delivery indication was prolonged second stage in 3143 (64%) cases and non-reassuring fetal heart rate in 1788 (36%). In the non-reassuring fetal heart rate group, there were higher rates of cephalohematoma, low 5-min Apgar-score, and asphyxia. In the prolonged second-stage group, there were higher rates of sepsis and post-partum hemorrhage. Composite neonatal birth trauma and maternal morbidity were higher for vacuum-assisted vaginal delivery following prolonged second stage. Following adjustment for confounders cephalohematoma (aOR 1.21, 95% CI 1.04-1.41), low 5-min Apgar-score (aOR 2.91, 95% CI 1.26-4.67) and asphyxia (aOR 1.81 95% CI 1.35-2.44) remained significant in the non-reassuring fetal heart rate group and neonatal sepsis remained significant for the prolonged second-stage group (aOR 1.77, 95% CI 1.38-2.27), p < 0.05 for all. However, there was no longer difference in the composite birth trauma, other neonatal or maternal morbidity.

CONCLUSION

The indication for vacuum-assisted vaginal delivery has an impact on neonatal outcome. While cephalohematoma, low 5' Apgar score, and asphyxia were more common in the non-reassuring fetal heart rate group, neonatal sepsis was more common in cases of prolonged second stage of labor.