From "eating expectantly" by bridget swinney:
"heavy caffeine consumption of 300 milligrams per day has been shown to cause small reductions in birth weight...Several studies have also suggested an association between caffeine and miscarriage."
a 12 oz coke has 31 mg, mountain dew has the most with 55 mg. Coffee has anywhere from 95mg (instant coffee) to 200 mg (starbucks drip). There is caffeine in tea, even snapple iced tea (48mg in 16 oz). There are small amounts of caffeine in hot cocoa, chocolate, and most anything coffee flavored (pudding, yogurt, ice cream).
The point is, just watch how much caffeine you take in because it adds up! :)