Performance of sonographically estimated fetal head circumference and estimated fetal weight in predicting the risk of unplanned cesarean and instrumental delivery in term nulliparous women

High rates of cesarean delivery, particularly primary cesarean delivery, are a concern for women and their care providers. 

In the present obstetric practise, estimated fetal weight by ultrasound is one of the determinants for the likelihood of operative vaginal delivery.

There are growing body of evidence showing that the fetal head, as the part directly interfacing with the maternal pelvis, plays a significant role when compared to fetal weight, in the progress and outcome of labor.