The effect of abortion on the incidence of pre-eclampsia.

The incidence of pre-eclampsia was studied in 9771 women that were pregnant for the first or second time. The protection offered by a previous pregnancy which ended in abortion was compared to that provided by a first pregnancy that proceeded to term. The rate of pre-eclampsia was 2.9% for primigravid women and was significantly lower (1.5%, p less than 0.001) for women giving birth for the second time. Adjusting by multiple regression for confounding factors (e.g., maternal age, social class, ethnic origin and smoking), the incidence of pre-eclampsia was also significantly lower (p = 0.038) following an induced abortion, but not following a spontaneous abortion.