Teratogens cross the placenta and cause malformations in a foetus and interfere with its development. When a pregnant woman drinks, the alcohol in her bloodstream passes freely through the placenta into the foetus’ blood. Because the foetus does not have a fully developed liver, it cannot filter out the toxins from the alcohol as the mother can. Instead, the alcohol circulates in the foetus’ blood system which can harm brain cells and damage the nervous system of the developing baby throughout the entire nine months of pregnancy.
