Gestational diabetes lowers VBAC odds. (23% Less Likely to Succeed).

LOS ANGELES -- Women attempting a vaginal birth after a previous cesarean delivery are more likely to need another C-section if they have gestational diabetes, but their chances of a successful vaginal birth are still good, Dr. Dominic Marchiano said.

Vaginal birth after a prior cesarean section (VBAC) succeeded in 68% of women with gestational diabetes and in 75% of women without gestational diabetes in a retrospective study of 25,079 pregnant women with a history of C-section. The study participants were seen at 16 community and university hospitals in a 4-year period, Dr. Marchiano reported during the annual meeting of the American College of Obstetricians and Gynecologists.

Stated another way, women with gestational diabetes were 23% less likely to have a successful VBAC.

The 6% of women who had gestational diabetes were less likely to attempt a trial of labor after a previous C-section: Only 40% of the 1,465 women with gestational diabetes attempted VBAC, compared with 54% of the 23,614 women without the disorder, said Dr. Marchiano of the University of Pennsylvania, Philadelphia.

The results of the study may have been affected by factors in the preselection of patients attempting VBAC such as prior pregnancy history, estimated fetal weight, or physician and patient preferences, he acknowledged.

Other limitations to the study include the inability to control for factors involved in the induction of labor, Dr. Marchiano said. Investigators also had no information about physicians' thresholds for halting a trial of labor already in progress to perform a ...