Placenta previa and previous cesarean section.

In a retrospective analysis over the six year period, January, 1973 to December, 1978, the incidence of placenta previa in cases with previous cesarean section (C.S.) was found to be 3.9 per cent as compared to an overall incidence of 1.9 per cent (p less than 0.01). The risk of placenta previa was greater in the pregnancy immediately following the cesarean section. The incidence of a morbidy adherent placenta was also significantly higher in these cases.