What maternal substance usage is contraindicated during pregnancy due to risks of fetal harm?

Alcohol consumption is contraindicated during pregnancy due to significant risks of fetal harm. Maternal alcohol intake during pregnancy can lead to a range of developmental disorders collectively known as Fetal Alcohol Spectrum Disorders (FASD). These disorders can result in physical, behavioral, and learning problems in the child that can last a lifetime.

Research has shown that there is no known safe amount of alcohol that can be consumed during pregnancy, and alcohol can cross the placenta, affecting the developing fetus at any stage of gestation. The risk of severe consequences increases with higher levels of consumption, but even low levels can pose dangers. Consequently, the recommendation is to avoid alcohol entirely during pregnancy to safeguard fetal health.

In contrast, moderate caffeine consumption is generally considered safe, over-the-counter sleep aids may be used under medical supervision, and prescription medications can be prescribed when the benefits outweigh the potential risks, particularly if they are deemed necessary for the mother's health. Therefore, the clear and established harm posed by alcohol makes its consumption during pregnancy particularly concerning.