Background: Coffee and caffeine have been inconsistently found to be associated with increased risk of clinical miscarriage—a potentially important association given the high prevalence of exposure.
Methods: Women were recruited before or early in pregnancy and interviewed regarding sources of caffeine, including assessment of changes over the perinatal period. We identified 2407 clinically-recognized pregnancies resulting in 258 pregnancy losses. We examined the relationship of coffee and caffeine intake with clinically-recognized pregnancy loss prior to 20 weeks’ completed gestation, using a discrete-time continuation ratio logistic survival model.
Results: Coffee and caffeine consumption at all 3 time points were unrelated to total miscarriage risk and the risk of loss after the interview. Reported exposure at the time of the interview was associated with increased risk among those with losses before the interview.
Conclusions: There is little indication of possible harmful effects of caffeine on miscarriage risk within the range of coffee and caffeine consumption reported, with a suggested reporting bias among women with losses before the interview. The results may reflect exposure misclassification and unmeasured heterogeneity of pregnancy losses.
From the *Department of Community and Preventive Medicine, Mount Sinai School of Medicine, New York, New York; Departments of †Epidemiology and ‡Biostatistics, University of North Carolina School of Public Health, Chapel Hill, North Carolina; §Division of Epidemiology, Statistics and Prevention Research, National Institute of Child Health and Human Development, Bethesda, Maryland; and ¶Department of Obstetrics and Gynecology, Vanderbilt University School of Medicine, Nashville, Tennessee.
Submitted 24 January 2007; accepted 14 August 2007.
Supported by the American Water Works Association Research Foundation under Contract 2579 and in part by the Intramural Research Program of the NIH, National Institute of Child Health and Human Development, and the National Institute of Environmental Health Sciences (training grant ES07018).
Correspondence: David A. Savitz, Department of Community and Preventive Medicine, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1057, New York, NY 10029. E-mail: email@example.com.