Experts say what's different about this study is that it shows a relatively small amount of caffeine per day can make a big difference.
Pregnant women have long been advised to limit their caffeine. Now they may be urged to give it up all together.
It's not clear why caffeine can cause miscarriage. It is known to cross the placenta and can be difficult for the fetus to metabolize.
So what's a pregnant mom looking for an energy boost to do? Doctors suggest taking a brisk walk, or yoga. Or go ahead and get that grande latte, but make it decaf.