Vaginal birth still the best

Dr. Brian M. Mercer, of Case Western Reserve University in Cleveland, Ohio, and colleagues studied the impact of prior vaginal birth after cesarean on outcomes of attempted vaginal births in subsequent pregnancies in 13 532 women.

For 9 012 women (67 percent), this was their first vaginal birth after cesarean - what doctors call "VBAC." Twenty-nine hundred women (21 percent) had a history of one prior VBAC, 1 058 (7,8 percent) had a history of two, 371 (2,7 percent) had a history of three, and 191 (1,4 percent) had a history of four or more VBACs.

Results showed that the frequency of VBAC success rose with increasing number of prior VBACs, from 63 percent with no prior VBACs to 88 percent for women with one and 91 percent for those with two or more prior VBACs.

The corresponding incidence of uterine rupture, a serious complication of labour, declined from 0,87 percent to 0,45 percent and 0,43 percent. The rates of other complications followed similar patterns with increasing number of prior VBACs.

In contrast, the investigators note, repeated cesarean deliveries are associated with higher risks of complications like placenta accreta (when the placenta implants too far into the uterus) and trauma to internal organs in the mother, as well as more frequent hysterectomies and blood transfusions.

"Women planning large families... should be reassured by the increasing success rates and decreasing risks associated with VBAC attempts in successive pregnancies," Mercer and his associates conclude.