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

Abstract

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.