Women who are trying to get pregnant might want to abstain from alcohol and should limit their caffeine consumption, according to a recent study by researchers at the Johns Hopkins University School of Hygiene and Public Health. The researchers have found that even small amounts of alcohol might impair conception and that caffeine could enhance the fertility-reducing properties of alcohol.
A team of researchers led by Rosemarie B. Hakim examined data provided by 124 women who participated in a long-term study of fertility. The women were employed at two semiconductor plants in Burlington, Vt., and East Fishkill, N.Y., between 1989 and 1991. They ranged in age from 23 to 41 and 21 percent of them smoked cigarettes, which are known to reduce fertility.
Women who took birth-control pills or used intrauterine devices were omitted from the study. Participants were required to submit daily urine specimens and to provide information about sexual intercourse and menstrual cycles. Consumption of cigarettes, alcohol and caffeine were analyzed separately to determine their effect on pregnancy.
Hakim and her colleagues found that women who consumed any alcohol and more than one cup of coffee per day achieved 10.5 pregnancies per 100 menstrual cycles, compared with 27 pregnancies per 100 menstrual cycles among women who drank no alcohol and less than one cup of coffee per day.
Overall, women who drank alcohol had a 50 percent reduction in conception. The decline in fertility increased with the amount of alcohol consumed, the researchers reported. But this study suggests that even two drinks per week can decrease fertility.
Caffeine consumption alone had a modest impact on fertility. Women who consumed the amount of caffeine equivalent to that contained in one or more cups of coffee had a slightly lower rate of conception than those who abstained from caffeine.
The authors, whose study was published last month in the journal Fertility and Sterility, write that their research suggests alcohol and caffeine have a greater effect on fertility than previous studies have suggested.