According to the Centers for Disease Control and Prevention (CDC), there is no known safe amount of alcohol to drink while pregnant. There is also no safe time during pregnancy to drink and no safe kind of alcohol. When a pregnant woman drinks alcohol, so does her unborn baby. Alcohol in the mother's blood passes through the placenta to the baby through the umbilical cord. Drinking alcohol during pregnancy can cause miscarriage, stillbirth, and a range of lifelong disorders, known as fetal alcohol spectrum disorders (FASDs).
Likewise, illegal drug use during pregnancy poses various risks for pregnant women and their babies. Some of these drugs can cause a baby to be born too small or too soon, or to have withdrawal symptoms, birth defects or learning and behavioral problems.