what is vertex in obg

In obstetrics, vertex refers to the position of the fetus in the womb during delivery. Specifically, it means that the fetus is in a head-down position, with its head first and facing the mothers spine, and its chin tucked to its chest. The vertex presentation is the ideal position for a vaginal delivery. The term "cephalic presentation" is also used to describe the head-down position of the fetus. The vertex presentation is the most common presentation observed in the third trimester, with about 95% of babies in this position at 36 weeks.