Objective: To examine the effects of alcohol and caffeine on conception.
Design: Prospective observational study.
Setting: Healthy volunteers in two manufacturing facilities.
Patient(s): One hundred twenty-four women who provided daily urine samples for measurement of steroid hormones and hCG, and prospective information about alcohol and caffeine consumption.
Main outcome measure(s): Probability of conception per 100 menstrual cycles.
Result(s): There was >50% reduction in the probability of conception during a menstrual cycle during which participants consumed alcohol. Caffeine consumption did not independently affect the probability of conception but may enhance alcohol's negative effect. Women who abstained from alcohol and consumed less than one cup of coffee or its equivalent per day conceived 26.9 pregnancies per 100 menstrual cycles compared with 10.5 per 100 menstrual cycles among those who consumed any alcohol and more than one cup of coffee per day.
Conclusions: This study revealed an independent dose-related negative effect of alcohol consumption on the ability to conceive. Our results suggest that women who are attempting to conceive should abstain from consuming alcohol.