Background. To determine whether the effect of live attenuated oral polio virus vaccine given to pregnant women increases pregnancy complications.Methods. A study of women who had been vaccinated against poliovirus during a national vaccination campaign and who had delivered by cesarean section in three obstetrical hospitals in southern Finland. One thousand seven hundred and forty‐seven vaccinated women (in three study cohorts), and their 2293 nonvaccinated controls (in two reference cohorts) were analyzed. Subjects are out of 22 000 deliveries evaluated earlier.Results. Vaccinated sectioned women did not show an excess of pregnancy complications. The mean rate of cesarean sections was 18.4% in the study cohorts and 18.9% in the reference cohorts counted from the 22 000 deliveries.Conclusions. Oral live attenuated polio virus vaccine does not increase pregnancy complications and is considered a safe alternative for vaccinating pregnant women.