Risks of preterm delivery and small-for-gestational age infants following abortion: a population study.

We examined hospital discharge records in 1980-81 for singleton third trimester deliveries in Scotland. We compared 3000 women who had previously experienced induced termination of pregnancy, and 4000 who had experienced spontaneous abortion with primigravidae and with women in their second pregnancy, their first having resulted in a livebirth. Two aspects of low birthweight were examined: delivery before the 37th completed week of gestation, and low birthweight for gestational age. Our comparisons were further controlled for maternal height, age, sex of infant, marital status and social class. Women with previous spontaneous abortions experienced significantly increased risk of preterm delivery but not of low birthweight for gestational age. Women with a history of induced abortion also experienced increased risk of preterm delivery, but for women aged 18-24 years, risk of low birthweight for gestational age was significantly reduced compared with primigravidae.