Caput succedaneum is swelling of the scalp in a newborn. It is most often brought on by pressure from the uterus or vaginal wall during a head-first (vertex) delivery.

A caput succedaneum is more likely to form during a long or hard delivery. It is more common after the membranes have broken. This is because the fluid in the amniotic sac is no longer providing a cushion for the baby’s head. Vacuum extraction done during a difficult birth can also increase the chances of a caput succedaneum.

A caput succedaneum may be detected by prenatal ultrasound, even before labor or delivery begins. It has been found as early as 31 weeks of pregnancy. Very often, this is due to an early rupture of the membranes or too little amniotic fluid. It is less likely that a caput will form if the membranes stay intact.