Effect of cigarette smoking and coffee drinking on time to conception.

To test the hypothesis that coffee consumption and cigarette smoking are associated with time to conception, we analyzed data collected from 1,341 primigravidas participating in the Child Health and Development Studies in the San Francisco Bay Area between 1959 and 1966. Women were interviewed in person about their reproductive and medical history, habits (smoking, coffee and alcohol consumption), and sociodemographic characteristics. Logistic regression models showed that after adjusting for covariates, women who smoked cigarettes had about one-half the fertility [odds ratio (OR) = 0.5-0.6] of nonsmoker-noncoffee drinkers for times to conception of 6 and 12 months, regardless of whether they drank coffee. On the other hand, coffee consumers who did not smoke did not have decreased fertility compared with nondrinkers who did not smoke (adjusted OR = 1.0-1.2). Coffee drinking did not increase the risk of delayed conception among smokers over the risk posed by the smoking exposure by itself (adjusted OR = 0.6-0.8). We observed an effect of smoking even at low doses (1-9 cigarettes per day). The present study adds to the evidence of an association between cigarette smoking and reduced fertility.