I've heard that caffeine is bad for you during pregnancy. Can I still drink coffee when I'm pregnant?
In Seattle, I used to have pregnant patients complain to me that they got dirty looks from baristas every time they tried to order a latte! Part of the knock on caffeine is due to older studies that were poorly designed. We know that smoking is more common in coffee drinkers than in non-drinkers, and smoking is associated with smaller babies. In studies that separated out the smokers and followed women's caffeine intake throughout their pregnancies, there were no associations between caffeine and reduced birth weight or premature delivery.
The other issue that's received recent media attention is whether caffeine intake during early pregnancy leads to miscarriages. These studies are limited by another phenomenon that occurs in pregnancy--first trimester nausea. It has long been known that there is a modestly lower rate of miscarriage in women who experience nausea in early pregnancy. Coffee is a common aversion among women with morning sickness. One study from Sweden claims to show that among non-smoking women who drank more coffee, there was a higher miscarriage rate. However, the women who miscarried also had much less nausea, and less aversion to all foods including coffee. It's probably not the caffeine that "caused" the miscarriages; it's the fact that women at higher risk for miscarriage (without nausea) tend to be able to keep their coffee consumption up.
There will likely never be the perfect study--no one will ever force a large group of pregnant women, nauseated or not, to drink coffee. Avoiding any unnecessary drug exposures (including caffeine), especially in the first trimester is a reasonable principle, but I do not believe there is any compelling evidence to suggest that a couple of cups of coffee a day is harmful in pregnancy. Avoiding any unnecessary drug exposures (including caffeine), especially in the first trimester is a reasonable principle, but I do not believe there is any compelling evidence to suggest that a cup of coffee a day (less than 270 mg of caffeine) is harmful in pregnancy.