Smoking does affect fecundity.

A total of 2198 mothers were interviewed at the 20th week of pregnancy and their smoking habits before pregnancy and the time from discontinuation of contraception to the beginning of the pregnancy were registered. This information was used to investigate whether smoking affects conception delay; i.e., fecundity and a multifactorial analysis were used. The longer the conception delay, the more significant was the deleterious effect of even light smoking, the odds ratio shifting from 1.1 at 6 months to 3.2 at 18 months. The effect of smoking on fecundity seemed to be mostly dose-dependent. In mothers becoming successfully pregnant in 12 months, both maternal and paternal smoking increased the risk of conception delay (OR 1.5 and 1.3), and the effect was potentiated by increasing age (OR 2.3 and 1.6). In addition to smoking, previous recurrent spontaneous abortions were also associated with fecundity.