Association between sonographic measurement of fetal head circumference and labor outcome

Objective To evaluate the association between sonographically measured head circumference (HC) and labor outcome. Methods In a retrospective study at a tertiary medical center in Israel, data were reviewed for all term singleton deliveries between July 2007 and December 2012 with HC measurements up to 7 days before delivery. HC was compared between women with operative vaginal delivery (OVD) or cesarean delivery for prolonged second stage and those with normal vaginal delivery. The impact of HC above the 75th percentile on pregnancy outcome was analyzed. Results The study included 2351 women, of whom 2045 (87.0%) had a normal vaginal delivery, 259 (11.0%) underwent OVD, and 47 (2.0%) cesarean. Each 10 mm increase in HC was associated with increased risk for obstetric intervention because of a prolonged second stage (adjusted odds ratio [aOR] 1.26; 95% confidence interval [CI] 1.08-1.46). HC above the 75th percentile was independently associated with increased odds of OVD (aOR 1.77; 95% CI 1.30-2.41), 1-minute Apgar score less than 7 (aOR 2.91; 95% CI 1.50-5.66), and neonatal asphyxia (aOR 2.19; 95% CI 1.02-4.71). Conclusion Term HC above the 75th percentile was associated with increased rates of obstetric interventions because of a prolonged second stage and might be associated with neonatal asphyxia.