American Journal of Obstetrics and Gynecology
Poster Session V984: Can maternal head circumference contribute to the prenatal prediction of successful spontaneous vaginal delivery-results from the prospective multicenter GENESIS study
Section snippets
Objective
Our group previously showed an association between fetal head circumference >90th centile and an increased risk of cesarean section. The objective of this study was to ascertain if there is an association between maternal head circumference (MHC) and spontaneous vaginal delivery (SVD), operative vaginal delivery (OVD), or adverse perinatal outcome.
Study Design
The GENESIS study was a prospective, blinded observational study carried out by the Perinatal Ireland Research Consortium from October 2012 to June 2015. A cohort of 2,336 nulliparous uncomplicated singleton pregnancies was recruited. Logistic regression was used to determine the risks of OVD and adverse perinatal outcome with increasing MHC. Linear and non-linear models for risk were explored.
Results
1,845 pregnancies which resulted in either an OVD (n=864) or an SVD (n=981) were compared. Mean MHC was 56.2cm (SD=1.8cm, range=50cm-65.5cm). There were 551 vacuum deliveries (59%), 248 forceps deliveries (29%) and 105 combined OVDs (12%). There was a linear increase in risk for OVD, OR=1.08 (95% CI=1.02-1.13, p=0.004) for every 1 cm increase in MHC (Table 1). This change in risk may be illustrated with categorizations of MHC: Those with a MHC < 54.4cm (Quartile 1) had a 42% risk compared to a
Conclusion
This study shows an association between increasing MHC and increased rates of OVD. There was no increase in adverse perinatal outcome. We therefore suggest considering the inclusion of MHC as part of routine antenatal assessment. This may aid decision-making for clinicians during labor.