Effects of cesarean section on fertility and abortions.

The impact of cesarean section on subsequent fertility and abortions was studied by comparing cohorts of women from two populations with unequal rates of cesarean section. After excluding women with strong confounding factors, all primiparae having had a cesarean section in 1973 and 1976 and matched controls were identified from the Swedish Birth Registry. The subsequent births in the next five and eight years were sought from the same registry and subsequent spontaneous abortions from the Hospital Inpatient Discharge Registry. There were fewer second children, subsequent children and twin deliveries in the cesarean section groups than in the control groups. The ratio of spontaneous abortions to births was somewhat higher in the cesarean section groups, but the difference was not statistically significant. Regardless of the different rates of cesarean section in the two populations, the 1973 and 1976 cohorts were similar. Apparently the findings were due not only to selection in the first cesarean section but possibly also to the operation itself.