Caffeine is a drug found in many foods, drinks and even some medications. It is a stimulant, which means it can keep people awake and it increases blood pressure and heart rate. It is also a diuretic and can lead to dehydration.
None of these things are recommended during pregnancy. When a woman is pregnant, what she ingests, her baby also ingests. So when she eats and drinks things containing caffeine, it passes through the placenta and reaches the baby. And while caffeine might not affect the pregnant woman very much, the baby’s metabolism isn’t as mature and cannot metabolize it as well.
According to The March of Dimes, women who are pregnant or trying to get pregnant should have no more than 200 mg of caffeine per day. This is the amount of caffeine in about a 12-ounce cup of coffee. While there is no conclusive evidence between the correlation of caffeine and miscarriages, it is better to play it safe with caffeine intake.