ABSTRACT: Two cohorts of healthy Swedish primiparae having a healthy child by cesarean section in 1973 (index women, N = 2592) and in 1976 (N = 3867) and matched vaginal delivery controls were identified from the Swedish Birth Register. The second births to these women occurring in the following five years were studied. The mean lengths of gestation were somewhat shorter and there were more problems during pregnancy, labor, and delivery among those with previous cesarean births (index women). Children born to the index women had a higher perinatal mortality and were smaller and less healthy. Comparison of the two cohorts suggests that the operation itself may have contributed to some of the problems. The decision to perform a cesarean section may have to take into account sequelae in a subsequent pregnancy.