Objective: Few studies on the long-term effects of cesarean sections exist. The purpose of this study was to investigate the occurrence of three long-term effects, ectopic pregnancy, placenta previa, and abruptio placentae, in the subsequent pregnancy.
Study design: This retrospective cohort study was based on two nationwide registers in Finland: the birth register and the hospital inpatient register. Women (n = 16,938) having had a cesarean section (exposed women) and a matched control group were identified from the birth register. The occurrence and outcome of the first subsequent pregnancy was determined from the 1987 to 1993 hospital inpatient register and the first subsequent birth from the 1987 to 1993 birth register.
Results: During the follow-up time in the hospital inpatient register, fewer exposed women had a completed pregnancy. Ectopic pregnancy was more common among the exposed women than among the controls (risk ratio 1.28). In the first subsequent birth abruptio placentae was more common among primiparous (at index the birth, risk ratios of 3.22 in hospital inpatient register and 2.41 in birth register) and multiparous women (4.52 in hospital inpatient register and 3.89 in birth register). Placenta previa was more common among primiparous exposed women than among control women (risk ratio 5.34 in hospital inpatient register and 3.78 in birth register).
Conclusions: Cesarean section is a modest risk factor for ectopic pregnancy and an important risk factor for placental problems.