Spontaneous cephalic version of breech presentation in the last trimester.

A prospective longitudinal investigation of spontaneous cephalic version from breech presentation in the last trimester is reported. All pregnancies were assessed with ultrasound in the 32nd week of gestation, and were thereafter checked weekly. Of the 310 singleton breech presentations identified at 32 weeks, spontaneous cephalic version occurred in 177 (57%) while breech presentation persisted in 133 patients (43%). Of 140 patients with a breech presentation at delivery 95% were already presenting by the breech in the 32nd week. Spontaneous cephalic version was less likely in pregnancies with extended fetal legs, low birth-weight, short umbilical cord and primiparity.