Increased risk of ectopic pregnancy with maternal cigarette smoking.

As part of a case-control study of ectopic pregnancy, we evaluated the potential etiologic role of cigarette smoking. Maternal cigarette smoking at the time of conception was associated with an increased risk of ectopic pregnancy with a dose-response relationship (adjusted odds ratios: 1.30 to 2.49). On the other hand, partner's smoking was not associated with ectopic pregnancy. The study provides a supplementary argument towards a causal effect of smoking in the development of ectopic pregnancy.