We know that smoking has all sorts of ill effects on people, and among other things there is evidence that it affects fertility. Weinberg and Gladen (1986) examined the effects of smoking on the ease with which women become pregnant. They took 586 women who had planned pregnancies, and asked them how many menstrual cycles it had taken for them to become pregnant after discontinuing contraception. They also sorted the women into whether they were smokers or nonsmokers. The data follow.

1 Cycle 2 Cycles 3 Cycles Total Smokers 29 16 55 100 Nonsmokers 198 107 181 486 Total 227 123 236 586 Does smoking affect the ease with which women become pregnant? (I do not recommend smoking as a birth-control device.)