Your baby's developing all the way through your pregnancy. Alcohol can be harmful at any stage. Drinking alcohol: damages your baby's developing cells which can affect how their brain and organs develop and how they look makes it more likely you'll have a miscarriage, or your baby will be born early or underweight can cause fetal alcohol spectrum disorder Even small amounts of alcohol can cross over from your body into your baby. The exact level of alcohol exposure that can lead to harm is not known with certainty, but the more you drink, the greater the possible harm.