C-Section and Subsequent Pregnancies.

Does cesarean section pose a risk for future pregnancy complications? This retrospective cohort study from Finland, based on nationwide birth and hospital inpatient registers for 1987 to 1993, compared 16,938 women who had undergone C-section with matched controls who had given birth vaginally.

Among women who had a subsequent pregnancy, those with a prior cesarean delivery were more likely to have ectopic pregnancy (risk ratio, 1.28), although the cesarean and control groups had similar rates of previous ectopic pregnancies. Primiparous women in the cesarean group were more likely than primiparous controls to have placental abruption in the next pregnancy (risk ratio, 2.41 based on the birth register and 3.22 based on the hospital register); the same was true among multiparous women (risk ratios for the cesarean group were 3.89 and 4.52 respectively). Placenta previa was more common among primiparas with a cesarean delivery than primiparous controls (3.78 vs. 5.34).

The absolute risks for all subgroups were 3.2% or less for ectopic pregnancy and 10% or less for placental problems.

-- American Journal of Obstetrics and Gynecology, May 1996