Alcohol readily crosses the placenta, and because of the design of fetal circulation, is not filtered by your baby’s liver before being sent to every other part of her body. The alcohol can cause damage to developing cells, particularly in your baby’s brain. Consuming alcohol during pregnancy is the leading cause of preventable birth defects.
For women who consume alcohol in large amounts during pregnancy, 4-5% of them with give birth to children affected by the full spectrum of Fetal Alcohol Syndrome (FAS). However, there is a wide range of symptoms that may develop when full spectrum FAS is not present. These include abnormal facial features and growth, learning or behavioral problems and damage to the central nervous system. Some children have problems that are not visibly obvious.
The amount and type of damage that is done appears to be dependant on the level of consumption, the pattern of alcohol exposure and the stage of pregnancy. Binge drinking, drinking large amounts of alcohol infrequently, is more highly associated with FAS. There appear to be vulnerable periods during the first and third trimesters, in which specific cells are damaged. For example, drinking in the first trimester is related to abnormal facial and brain development. Both the first and third trimester are associated with damage to certain structures in the brain.
The evidence about low to moderate alcohol consumption (1-2 glasses per day) is still inconclusive. While not associated with facial abnormalities, there is evidence of possible behavior changes and developmental delays in children whose mother’s consumed low amounts of alcohol throughout pregnancy. Because the research has not yet determined what levels may be safe, the United States Center for Disease Control recommend that women who are or may become pregnant avoid drinking alcohol.