Does caffeine and alcohol intake before pregnancy predict the occurrence of spontaneous abortion?

BACKGROUND Consumption of caffeine and alcohol is suspected to affect pregnancy outcome. Use of both stimulants is widespread and even minor effects on fetal viability are of public health interest. METHODS We performed a nested case-control study using prospective data from a population-based cohort comprising 11088 women aged 20-29 years. From this cohort, women who experienced either a spontaneous abortion (n = 303) or who gave birth (n = 1381) during follow-up [mean time: 2.1 years (range: 1.6-3.4)] were selected. Associations between self-reported exposures to caffeine and/or alcohol at enrolment and spontaneous abortion were analysed by means of logistic regression. RESULTS Compared with women with a pre-pregnancy intake of <75 mg caffeine per day, the adjusted odds ratio (95% confidence interval) for spontaneous abortion was 1.26 (0.77-2.06), 1.45 (0.87-2.41), 1.44 (0.87-2.37) and 1.72 (1.00-2.96) for a pre-pregnancy intake on 75-300, 301-500, 501-900 and >900 mg caffeine per day respectively (P = 0.05 for trend). A pre-pregnancy intake of alcohol was not a predictor for spontaneous abortion. CONCLUSIONS A high intake of caffeine prior to pregnancy seems to be associated with an increased risk of spontaneous abortion, whereas a low-to-moderate alcohol intake does not influence the risk.