Pregnant women consuming over eight cups of coffee a day risk spontaneous abortion and stillbirth.
According to a Danish study, fetal death was twice as likely among heavy coffee drinkers relative to pregnant women who did not drink coffee.
Adjusting for other risk factors weakened the association somewhat, but heavy coffee drinkers remained at 59 percent greater risk of fetal death, Dr. Bodil Hammer Bech of the University of Aarhus and colleagues report in the American Journal of Epidemiology.
Pregnant women who drank four to seven cups daily had a 33 percent increased risk of fetal death. Denmark currently has an official policy warning women to restrict their coffee intake to three cups or less daily.
Many studies in the past have linked coffee drinking to undesirable pregnancy outcomes, and caffeine harming a fetus, the risks of coffee drinking in pregnancy were questioned.
The researchers surveyed 88,482 women enrolled in the Danish National Birth Cohort, among whom there were 1,102 fetal deaths. The women were interviewed about coffee consumption and potentially confounding factors, such as alcohol consumption and smoking, at about 16 weeks' gestation.
Of the women surveyed, 55.4 percent reported drinking no coffee during pregnancy, while 31.4 percent consumed one-half to three cups daily. Thirteen percent of the women drank more than three cups of coffee daily, while 3.4 percent drank eight or more cups a day.
After adjustment, it was found that women who took one-half to three cups a day had a 3 percent increased risk of fetal death; those who consumed four to seven cups had a 33 percent increased risk; and those who drank eight or more cups had a 59 percent greater risk of fetal death. The association was strongest for fetal deaths after 20 weeks gestation.
Interestingly, the researchers did not find a link between tea or cola consumption and fetal death, which suggests that caffeine may not be the exposure of interest. "Coffee contains a number of chemical compounds. Further studies would try to isolate a caffeine effect from a non-caffeine effect," a researcher said.