The latest study among many on caffeine and health indicates beverages containing caffeine can be a safe choice for pregnant women. In the September 1997 issue of Epidemiology, Laura Fenster, Ph.D., and colleagues examine the relationship between moderate and heavy caffeine consumption (up to 300 mg and over 300 mg) and spontaneous abortion in 5,342 women interviewed in the first trimester of pregnancy. The research, which looked at the effects of consuming both caffeinated beverages and decaffeinated coffee, considered confounding factors such as alcohol, smoking and nausea.
Dr. Fenster and her colleagues specifically considered nausea as a confounding factor in measuring the association between caffeine and spontaneous abortion. Previous research indicated nausea as a factor for decreased caffeine consumption during pregnancy, because women who are nauseated are less likely to consume foods and beverages which they usually enjoy. The current study did not closely monitor nausea as a confounding factor, but it was recognized that nausea may play an important role.
With or without the presence of nausea, Dr. Fenster concluded that, "neither total estimated nor individual caffeinated beverage consumption during the first trimester was associated with an appreciable risk for spontaneous abortion." An unexpected association between the consumption of three or more cups of decaffeinated coffee and spontaneous abortion was not completely explained by characteristics of some decaffeinated coffee drinkers, such as age, alcohol and cigarette usage and race. The authors could not find a biological reason for the finding. Dr. Fenster concluded that the aberrant association was most likely due to bias in the research data.