Induced abortions, miscarriages, and tobacco smoking as risk factors for secondary infertility.

Abstract

STUDY OBJECTIVE--The aim was to determine whether induced abortions could increase the risk of secondary infertility. DESIGN--This was a case-control study; cases were women with secondary infertility, individually matched to two controls who were currently pregnant. Each participant was interviewed by one of two medical doctors using a questionnaire that sought information on their demographic, socioeconomic, medical, and reproductive status. The data were analysed by conditional logistic regression. SETTING--The study took place in the Alexandra Maternity Hospital in Athens, Greece, in 1987-88. PARTICIPANTS--84 women consecutively admitted with secondary infertility and 168 pregnant controls took part. MAIN RESULTS--Eight cases and no controls reported a previous ectopic pregnancy, confirming that the occurrence of a pregnancy of this type dramatically increases the risk of secondary infertility. Furthermore, the occurrence of either induced abortions or spontaneous abortions independently and significantly increased the risk of subsequent development of secondary infertility. The logistic regression adjusted relative risks (and 95% confidence intervals) for secondary infertility were 2.1 (1.1-4.0) when there was one previous induced abortion and 2.3 (1.0-5.3) when there were two previous induced abortions. Tobacco smoking significantly increased the risk of secondary infertility, the adjusted relative risk being 3.0 (1.3-6.8). CONCLUSIONS--Legalised induced abortions, as currently practised in Greece, appear to increase slightly the relative risk of secondary infertility.