The authors earlier conducted a retrospective study of time to pregnancy among a group of pregnant women in Minnesota, in order to investigate the relation between cigarette smoking and fecundability. Further analysis of these data shows that women who had been exposed as children to cigarette smokers had increased fertility. This finding lacks biologic plausibility. However, the authors found a similar association in a group of North Carolina women whose fecundability had been measured prospectively. Furthermore, both groups showed an apparent dose-response effect. The authors briefly describe this unexpected finding so that it might be more fully explored in other studies.