Do Birth Outcomes Predicted by Occipital Position Inform Definitions of Occiput Posterior and Occiput Transverse?

Fetal head position significantly influences birth outcomes, with higher rates of complications observed when the fetal head is in the Occiput Posterior (OP) position compared to Occiput Transverse (OT) or Occiput Anterior (OA) positions. There is no consensus in the current literature on the precise rotational point at which the fetal occiput shifts from posterior to transverse, reducing clarity in both scientific and clinical communication. Different studies employ varying definitions of these positions, which affects management decisions. This study aims to determine if a definable threshold exists between the directly posterior and directly transverse positions that correlates with different birth outcomes, thereby proposing a consistent and clinically useful definition for OP versus OT. We analyzed ultrasound data from 570 patients at full dilatation from five previous studies, correlating the angle of the fetal occiput (noted on a clock-face) with birth outcomes. Adverse outcomes were defined as cesarean delivery, instrumental vaginal delivery, significant postpartum hemorrhage (500 ml or more), obstetric anal sphincter injury, five-minute Apgar scores <7, arterial cord pH <7, base excess less than -12, or neonatal intensive care unit admission. The analysis was conducted using SAS version 9.4. The study found a continuous relationship between the fetal occipital angle and adverse birth outcomes without a distinct threshold separating OP from OT positions. No clear inflection point was demonstrated in pregnancy outcomes between OT and OP. The relationship between the angle of occiput position and pregnancy outcomes was continuous: the closer the fetal head was to directly OP, the higher the likelihood of adverse outcomes. Given the lack of a clear cut-off and to improve consistency in future research, we recommend dividing the occiput position into four quadrants of 90 degrees each. This classification could standardize reporting and potentially improve clinical decision-making regarding fetal position during labor.

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.

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.

Transverse position. Using rotation to aid normal birth-OUTcomes following manual rotation (the TURN-OUT trial): a randomized controlled trial

BACKGROUND

The fetal occiput transverse position in the second stage of labor is associated with adverse maternal and perinatal outcomes. Prophylactic manual rotation in the second stage of labor is considered a safe and easy to perform procedure that has been used to prevent operative deliveries.

OBJECTIVE

This study aimed to determine the efficacy of prophylactic manual rotation in the management of the occiput transverse position for preventing operative delivery. We hypothesized that among women who are at ≥37 weeks' gestation with a baby in the occiput transverse position early in the second stage of labor, manual rotation compared with a "sham" rotation will reduce the rate of operative delivery.

STUDY DESIGN

A double-blinded, parallel, superiority, multicenter, randomized controlled clinical trial in 3 tertiary hospitals was conducted in Australia. The primary outcome was operative (cesarean, forceps, or vacuum) delivery. Secondary outcomes were cesarean delivery, serious maternal morbidity and mortality, and serious perinatal morbidity and mortality. Outcomes were analyzed by intention to treat. Proportions were compared using χ² tests adjusted for stratification variables using the Mantel-Haenszel method or Fisher exact test. Planned subgroup analyses by operator experience and technique of manual rotation (digital or whole hand rotation) were performed. The planned sample size was 416 participants (trial registration: ACTRN12613000005752).

RESULTS

Here, 160 women with a term pregnancy and a baby in the occiput transverse position in the second stage of labor, confirmed by ultrasound, were randomly assigned to receive either a prophylactic manual rotation (n=80) or a sham procedure (n=80), which was less than our original intended sample size. Operative delivery occurred in 41 of 80 women (51%) assigned to prophylactic manual rotation and 40 of 80 women (50%) assigned to a sham rotation (common risk difference, -4.2% [favors sham rotation]; 95% confidence interval, -21 to 13; P=.63). Among more experienced proceduralists, operative delivery occurred in 24 of 47 women (51%) assigned to manual rotation and 29 of 46 women (63%) assigned to a sham rotation (common risk difference, 11%; 95% confidence interval, -11 to 33; P=.33). Cesarean delivery occurred in 6 of 80 women (7.5%) in the manual rotation group and 7 of 80 women (8.7%) in the sham group. Instrumental (forceps or vacuum) delivery occurred in 35 of 80 women (44%) in the manual rotation group and 33 of 80 women (41%) in the sham group. There was no significant difference in the combined maternal and perinatal outcomes. The trial was terminated early because of limited resources.

CONCLUSION

Planned prophylactic manual rotation did not result in fewer operative deliveries. More research is needed in the use of manual rotation from the occiput transverse position for preventing operative deliveries.

Intrapartum ultrasound for the diagnosis of cephalic malpositions and malpresentations

Fetuses with malpresentation and malposition during labor represent important clinical challenges. Women with fetuses presenting with malpresentation or malposition are at risk of increased perinatal complications, such as cesarean delivery, failure of operative vaginal delivery, neonatal acidemia, and neonatal intensive care admission. Intrapartum ultrasound has been found to be more reliable than digital examination in assessing malpresentation and malposition. The use of intrapartum ultrasound to assess fetal position and presentation, in addition to fetal attitude, to predict and aid in decision making regarding delivery can help in improving management decision making. Cephalic malpresentation and malposition is a unique subset of fetal orientation and can benefit from intrapartum ultrasound identification and assessment for delivery.

Epidurals: Do They or Don't They Increase Cesareans?

The controversy over whether epidurals increase the risk of cesarean has raged since the 1970s. This article provides a history of of the early observational research designed to answer this question and an in-depth analysis of the most recent randomized control trials. Based on the research, the author concludes that we cannot assure women that epidurals do not increase the risk of cesarean.

Prediction of delivery mode by ultrasound-assessed fetal position in nulliparous women with prolonged first stage of labor

OBJECTIVES

To ascertain if fetal head position on transabdominal ultrasound is associated with delivery by Cesarean section in nulliparous women with a prolonged first stage of labor.

METHODS

This was a prospective observational study performed at Stavanger University Hospital, Norway, and Addenbrooke's Hospital, Cambridge, UK, between January 2012 and April 2013. Nulliparous pregnant women with a singleton cephalic presentation at term and prolonged labor had fetal head position assessed by ultrasound. The main outcome was Cesarean section vs vaginal delivery, and secondary outcomes were association of fetal head position with operative vaginal delivery and duration of remaining time in labor.

RESULTS

Fetal head position was assessed successfully by ultrasound examination in 142/150 (95%) women. In total, 19/50 (38%) women with a fetus in the occiput posterior (OP) position were delivered by Cesarean section compared with 16/92 (17%) women with a fetus in a non-OP position (P = 0.01). On multivariable logistic regression analysis, the OP position predicted delivery by Cesarean section with an odds ratio (OR) of 2.9 (95% CI, 1.3-6.7; P = 0.01) and induction of labor with an OR of 2.4 (95% CI, 1.0-5.6; P = 0.05). Fetal head position was not associated with operative vaginal delivery or with remaining time in labor. The agreement between a digital and an ultrasound assessment of OP position was poor (Cohen's kappa = 0.19; P = 0.18).

CONCLUSION

OP fetal head position assessed by transabdominal ultrasound was significantly associated with delivery by Cesarean section.

Transverse occiput position: Using manual Rotation to aid Normal birth and improve delivery OUTcomes (TURN-OUT): A study protocol for a randomised controlled trial

BACKGROUND

Fetal occiput transverse position in the form of deep transverse arrest has long been associated with caesarean section and instrumental vaginal delivery. Occiput transverse position incidentally found in the second stage of labour is also associated with operative delivery in high risk cohorts. There is evidence from cohort studies that prophylactic manual rotation reduces the caesarean section rate. This is a protocol for a double blind, multicentre, randomised, controlled clinical trial to define whether this intervention decreases the operative delivery (caesarean section, forceps or vacuum delivery) rate.

METHODS/DESIGN

Eligible participants will be ≥37 weeks pregnant, with a singleton pregnancy, and a cephalic presentation in the occiput transverse position on transabdominal ultrasound early in the second stage of labour. Based on a background risk of operative delivery of 49%, for a reduction to 35%, an alpha value of 0.05 and a beta value of 0.2, 416 participants will need to be enrolled. Participants will be randomised to either prophylactic manual rotation or a sham procedure. The primary outcome will be operative delivery. Secondary outcomes will be caesarean section, significant maternal mortality and morbidity, and significant perinatal mortality and morbidity. Analysis will be on an intention-to-treat basis. Primary and secondary outcomes will be compared using a chi-squared test. A logistic regression for the primary outcome will be undertaken to account for potential confounders. This study has been approved by the Ethics Review Committee (RPAH Zone) of the Sydney Local Health District, Sydney, Australia, (protocol number: X110410).

DISCUSSION

This trial addresses an important clinical question concerning a commonly used procedure which has the potential to reduce operative delivery and its associated complications. Some issues discussed in the protocol include methods of assessing risk of bias due to inadequate masking of a procedural interventions, variations in intervention efficacy due to operator experience and the recruitment difficulties associated with intrapartum studies.

TRIAL REGISTRATION

This trial was registered with the Australian New Zealand Clinical Trials Registry (identifier: ACTRN12613000005752 ) on 4 January 2013.