Maternal height, birthweight, obstetric conjugate and their influence on the management of parturients with a previous cesarean scar.

A retrospective analysis was made of the second deliveries of 492 women who had previously undergone emergency cesarean section with a clinical indication of cephalopelvic disproportion and had undergone X-ray pelvimetry. In their index (second) pregnancy, 234 (47%) had an elective cesarean section; 122 (25%) gave birth vaginally and 136 (28%) had undergone an emergency cesarean section. Maternal height had a moderate value as a surrogate measure of pelvic capacity. A trial labor was more often allowed in women with larger obstetrical conjugate (inlet) measurements but likelihood of a successful outcome of labor was not influenced by the above pelvic measurements. A baby weighing more than 4000 g was associated with a greatly reduced chance of a vaginal delivery. The study confirms the limitations of X-ray pelvimetry measurements and proposes that antenatal estimation of fetal size may be of benefit in determining the likelihood of success in a trial labor.