A meta‐analysis of risk of pregnancy loss and caffeine and coffee consumption during pregnancy

BACKGROUND: Previous reports of the relationship between pregnancy loss and caffeine/coffee consumption have been inconsistent. OBJECTIVES: To evaluate the association between pregnancy loss and caffeine and coffee consumption. SEARCH STRATEGY: PubMed was searched for reports published before September 2014, with the keywords "caffeine," "coffee," "beverage," "miscarriage," "spontaneous abortion," and "fetal loss." SELECTION CRITERIA: Case-control and cohort studies were included when they had been reported in English, the exposure of interest was caffeine/coffee consumption during pregnancy, the outcome of interest was spontaneous abortion or fetal death, and multivariate-adjusted odds ratios (ORs) or risk ratios were provided or could be calculated. DATA COLLECTION AND ANALYSIS: Data were extracted and combined ORs calculated. MAIN RESULTS: Overall, 26 studies were included (20 of caffeine and eight of coffee). After adjustment for heterogeneity, caffeine consumption was associated with an increased risk of pregnancy loss (OR 1.32, 95% confidence interval [CI] 1.24-1.40), as was coffee consumption (OR 1.11, 95% CI 1.02-1.21). A dose-response analysis suggested that risk of pregnancy loss rose by 19% for every increase in caffeine intake of 150 mg/day and by 8% for every increase in coffee intake of two cups per day. CONCLUSIONS: Consumption of caffeine and coffee during pregnancy seems to increase the risk of pregnancy loss.