According to a study published in the British Medical Journal, drinking moderate amounts of coffee while pregnant will not pose harm to a developing baby. The study followed over 1,200 pregnant women who drank at least three cups of coffee a day, and compared these women to a group of those drinking decaffeinated coffee or no coffee during pregnancy. There was no significant difference between the size of babies born to either of these groups and no apparent difference between the risk of preterm labor. The study did find, however, that women who smoked ten cigarettes a day at the onset of pregnancy were more likely to deliver smaller babies, and this risk was increased if the women were also coffee drinkers. Among other pregnancy risks associated with smoking cigarettes are miscarriage, preterm labor, bleeding,abnormal placenta position and fetal malformations.

Source: MSNBC.com