Although regular smoking and alcohol dependence are highly correlated (Grucza & Beirut, 2006; Madden et al., 2000), history of regular smoking was associated with earlier first childbirth, particularly in the younger cohort. In the older cohort, regular smoking was associated with earlier reproduction, with pronounced effects for women through age 19, and for men, through age 29. A slight albeit significant delay was observed for women in the older cohort, but after age 20. For younger women and men, effects of regular smoking were strongest before age 20.
