Fetal Head Circumference as a Predictor of Operative Delivery

When vaginal delivery poses a danger to the mother or newborn infant, operative delivery (instrumental or cesarean section) is indicated. Some specific indications for operative delivery include prolonged second-stage of labor, suspected compromise of the fetus, health-related disorders of the fetus or the mother that justify shortening of the second-stage of active labor and more. In cases where cephalo-pelvic disproportion (CPD) is suspected or when instrumental delivery is not possible or fails, cesarean section plays a critical role . Studies trying to identify women at greatest risk of CPD have concluded that neither x ray, nor computed tomography or magnetic resonance imaging have a proven value in labor management or in predicting clinical outcomes . Previous studies assessing fetal factors that are associated with operative delivery have focused mainly on estimated fetal weight to predict macrosomia. Nonetheless, ultrasound estimation of the fetal weight was shown to differ by as much as 20% from actual birth weight, and identifying cases with suspected fetal macrosomia, other than for diabetic pregnancies, was not found to improve labor outcome . As weeks may possibly elapse between the time of last antenatal assessment and onset of labor, a further challenge is related to the timing of ultrasound assessment. Several studies have shown an association between increased Fetal Head Circumference (FHC) and prolonged second-stage of labor, instrumental delivery and cesarean section . However, FHC can only be acquired following delivery and has no predictive value for interventions in labor.