When you're pregnant and drink alcohol, it enters your bloodstream and reaches your developing fetus by crossing the placenta. Because a fetus metabolizes alcohol more slowly than an adult does, your developing baby's blood alcohol concentrations are higher than those in your body. Alcohol also interferes with the delivery of oxygen and optimal nutrition to your baby's developing tissues and organs, including the brain.

The more you drink while pregnant, the greater the risk to your unborn baby. The risk is present at any time during pregnancy. However, impairment of facial features, the heart and other organs, including the bones, and the central nervous system may occur as a result of drinking alcohol during the first trimester. That's when these parts of the fetus are in key stages of development. In the early weeks of the first trimester, many women may not be aware that they're pregnant.

May. 21, 2011