EFFECTS OF CIGARETTE-SMOKING, CAFFEINE CONSUMPTION, AND ALCOHOL INTAKE ON FECUNDABILITY

Data from the Ontario Farm Family Health Study were analyzed to determ ine whether smoking, caffeine, or alcohol use among men and women affe ct fecundability (the monthly probability of conception). In this retr ospective cohort study of farm couples in Ontario, Canada, the farm op erator, husband, and wife completed questionnaires during 1991-1992, y ielding information on 2,607 planned pregnancies that had occurred ove r the previous 30 years. Fecundability ratios were calculated using an analog of the Cox proportional hazards model. Cigarette smoking among women and men was associated with decreased fecundability (fecundabil ity ratio = 0.90, 95% confidence interval (CI) 0.82-0.98 and fecundabi lity ratio = 0.88, 95% CI 0.81-0.95, respectively), Caffeine consumpti on of 100 mg or less versus more than 100 mg in women and men was not associated with fecundability (fecundability ratio = 0.98, 95% CI 0.91 -1.07 and fecundability ratio = 1.05, 95% CI 0.97-1.14, respectively), Decreases were observed among women who were coffee drinkers (fecunda bility ratio = 0.92, 95% CI 0.84-1.00) and men who were heavy tea drin kers (fecundability ratio = 0.85, 95% CI 0.69-1.05), regardless of caf feine content. Alcohol use among women and men was not associated with fecundability. These data are consistent with previous studies of the adverse effect of tobacco on fecundability in female smokers and sugg est an effect of smoking among males. Continued evaluation of coffee a nd tea is warranted to address constituents other than caffeine.