Perhaps the most significant factor influencing the Caesarean rate, many experts agree, is the practice of performing Caesarean sections in each subsequent delivery after a woman has had a first. The practice follows an old medical dictum: "Once a section, always a section." Dr. Warren Pearse, executive director of the American College of Obstetricians and Gynecologists, a leading professional group, said an appropriate Caesarean section rate would be between 12% and 15% of all births. But Pearse refused to join in characterizing anything over that as "unnecessary."

There is a small risk of rupture of the uterus in a vaginal delivery after an initial Caesarean, [Bruce Flamm] said, but maternal or infant deaths from such events have been rare in recent years and vaginal-after-Caesarean birth is widely viewed as an extremely safe procedure that avoids exposing a woman and her child to the risks of abdominal surgery.

Statewide, Kaiser hospitals achieved a 1984 Caesarean rate of 17.9%, a development Flamm said has been the result of more aggressive in-hospital review of Caesarean sections performed by staff physicians and much more frequent use of vaginal birth after initial Caesarean deliveries.