When a pregnant mother uses alcohol, tobacco or an illicit drug, the substance can travel through the human placenta and enter the bloodstream of the fetus, causing birth defects, slowing growth and development, and resulting in intellectual impairment of the child when he reaches school age, reports PubMed. No amount of these substances are safe for pregnant mothers, but ingesting larger amounts can cause greater damage.
Some legal drugs can have a more detrimental effect than illicit substances. Alcohol use during pregnancy can cause facial dysmorphic features, developmental delay and mental impairment, according to PubMed Central. Tobacco use can cause decreased birth weight and a higher instance of sudden infant death syndrome.
Illegal drugs are detrimental to a developing fetus as well, continues PubMed Central. Cocaine use can cause emotional disruption and cognitive impairment as the child grows, and it increases the rate of sudden infant death syndrome. Children with prenatal exposure to methamphetamine often exhibit increased stress and decreased arousal, and they tend to perform much lower in school and have decreased social interactions.
Prescription drugs can also cause problems in prenatal development, reports PubMed Central. They may increase the risk for neural tube defects and autism spectrum disorder.