One C-Section Leads to Another? July 5, 2001 -- Women who have given birth by cesarean section will have to decide whether to undergo a repeat C-section or attempt vaginal delivery with their next pregnancy. For expectant moms leaning against another C-section, take note: The greatest risk with attempting labor after C-section is that of tearing the uterus; and according to a new study out this week, the risk is much greater than experts originally thought.

Women's risk of tearing their uterus, called a uterine rupture, increases significantly if they decide not to have another C-section, says Mona Lydon-Rochelle, PhD, lead author of the new report, which appears in the July 5 issue of The New England Journal of Medicine. And the risk is even greater among women who are induced.

Each year, about 60% of women who have had a C-section attempt labor with a subsequent pregnancy, says Lydon-Rochelle. And although C-sections cause discomfort and longer recovery times, uterine rupture puts the baby's life at risk and can cause serious injury to the woman. Rupture also can lead to the need for blood transfusions and hysterectomy.

In her study of more than 20,000 women with one previous C-section, Lydon-Rochelle found the risk of uterine rupture was more than three times higher for those who went into spontaneous labor than those who had a repeat C-section.

Among women who had to be induced, the risk was even greater. Women induced with an agent containing a substance called a prostaglandin were 15 times more likely to experience uterine rupture and those induced with a nonprostaglandin agent were almost five times more likely compared with women who had a repeat C-section.

Michael F. Greene, MD, is director of maternal-fetal medicine at Boston's Massachusetts General Hospital. In an editorial he wrote to accompany the new findings, he says the results are "perfectly consistent" with previous studies, with one exception.

"What's new and different about this study is ... the estimate of risk of uterine rupture associated with prostaglandin induction of labor," Greene tells WebMD. "That kind of shakes things up."