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How does fetal alcohol syndrome develop during pregnancy?

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Infographic showing estimated lives saved by childhood vaccinations worldwide from 1974 to 2024, with syringe-shaped bars for each disease. Measles tops the list at 93.71 million lives saved, followed by tetanus, whooping cough, and others, for a total of 153.84 million lives saved. — childhood disease and disorder Vaccines and the estimates of lives saved over the period 1974–2024.

Fetal alcohol syndrome (FAS) develops when a mother consumes alcohol around the time of conception or during pregnancy. The condition is caused by the toxic effects of ethyl alcohol or its metabolic byproduct, acetaldehyde, on the developing embryo or fetus.1

These substances interfere with normal development, leading to a range of congenital abnormalities, including impaired growth, central nervous system damage, and characteristic facial features. Because it remains unclear if any amount of alcohol is safe at any stage of pregnancy, medical experts and health authorities, such as the U.S. Surgeon General, advise total abstinence from alcohol for those who are pregnant or planning to become pregnant to prevent these preventable fetal alcohol spectrum disorders. Protecting the health of the developing fetus is a fundamental ethical responsibility, as alcohol exposure can cause irreversible harm to the child's physical and neurological development.123