There's long been debate on the safety of drinking coffee while pregnant.  A new study (http://www.newscientist.com/article/dn13206-coffee-can-double-risk-of-miscarriage.html) finds that two or more cups of coffee a day while pregnant will more than double your chances of miscarriage.  Specifically, it appears to be the caffeine, since soda pop, tea, and hot chocolate had similar results.