Around 4 percent of women in the United States take illegal drugs while pregnant, the March of Dimes states. A number of pregnant women who take illegal drugs also use legal drugs, such as tobacco and alcohol. All these drugs cross the placenta and can affect the fetus prenatally, causing withdrawal symptoms at birth. Many of the children born also have long-term effects from maternal drug use in pregnancy.
Some drugs more frequently cause birth defects than others, notably alcohol, the most common cause of preventable birth defects in the United States, affecting between 0.5 and two children per thousand births, the Office of the Surgeon General reported in 2005. Fetal Alcohol Syndrome causes facial malformations, learning difficulties, behavioral issues and small stature. Amphetamines, such as Ecstasy, and methamphetamines may cause congenital heart defects, cleft lip and palate or clubfoot in some infants, according to the March of Dimes. Cocaine exposure may cause urinary tract defects.
Sudden Infant Death Syndrome
The risk of sudden infant death syndrome, or SIDS, is increased as much as twentyfold in women who used opiates, such as heroin, during pregnancy, author and pediatrician William Sears, M.D., reports on his website. Tobacco use also increases the risk of SIDS, he adds.
A number of studies indicate that prenatal drug exposure can cause learning disabilities as children grow. A 2002 article in the "Journal of the American Medical Association" by lead author Lynn Singer, Ph.D., of Case Western Reserve University Department of Pediatrics found that cocaine-exposed children were twice as likely to have cognitive delays compared to children not prenatally exposed to cocaine. Children prenatally exposed to heroin may also have long-term learning disabilities, the March of Dimes reports.
Learning disabilities and behavioral issues often go hand in hand. One study reported in the 2007 "Journal of Behavioral Pediatrics" by lead author Dr. Michael Lewis reported an increase in high-risk behavior, such as aggression, disregard for safety precautions and substance abuse, in 10-year-old males exposed to cocaine prenatally compared to boys not exposed to cocaine. This issue was found only in boys.
Exposure to marijuana in the first and third trimesters of pregnancy can increase the risk of depression in children, lead author Kimberly Gray of the National Institute of Environmental Health Sciences reported in the May-June 2005 issue of "Neurotoxicology and Teratology."
Fetal alcohol syndrome can cause growth retardation and short stature. A 2007 University of Pittsburgh study by Dr. Gale Richardson in "Pediatrics" reported that children exposed to cocaine during the first three months of pregnancy had slower growth rates than those not exposed to cocaine.