Marijuana is the most frequently used illicit drug among women of childbearing age in the United States (1). Some studies suggest that use of marijuana during pregnancy may slow fetal growth and slightly decrease the length of pregnancy (possibly increasing the risk of premature birth). These effects are seen mainly in women who use marijuana regularly (six or more times a week) (2).
There have been a limited number of studies following marijuana-exposed babies through childhood. Some did not find any increased risk of learning or behavioral problems. However, others found that children who were exposed to marijuana before birth are more likely to have subtle problems that affect their ability to pay attention (2, 3). Exposed children do not appear to have a decrease in IQ.
The use of Ecstasy, methamphetamine and other amphetamines has increased dramatically in recent years. There have been few studies on how Ecstasy may affect pregnancy. One small study did find a possible increase in congenital heart defects and, in females only, of a skeletal defect called clubfoot (4). Babies exposed to Ecstasy before birth also may face some of the same risks as babies exposed to other types of amphetamines.
The long-term outlook for these children is not known. Children who are born with low birthweight are at increased risk of learning and other problems. Children with reduced head circumference are more likely to have learning problems than those with low birthweight and normal head size (5). More studies are needed to determine the long-term outlook for children exposed to amphetamines before birth.
Women who use heroin during pregnancy greatly increase their risk of serious pregnancy complications. These risks include poor fetal growth, premature rupture of the membranes (the bag of waters that holds the fetus breaks too soon), premature birth and stillbirth.
The outlook for these children depends on a number of factors, including whether they suffered serious prematurity-related or other complications. Some studies suggest that children exposed to heroin before birth are at increased risk of learning and behavioral problems (6).
Cocaine use during pregnancy can affect a pregnant woman and her baby in many ways. During the early months of pregnancy, cocaine may increase the risk ofmiscarriage. Later in pregnancy, it may trigger preterm labor (labor that occurs before 37 completed weeks of pregnancy) or cause the baby to grow poorly. As a result, cocaine-exposed babies are more likely than unexposed babies to be born prematurely and with low birthweight. Premature and low-birthweight babies are at increased risk of health problems during the newborn period, lasting disabilities such as intellectual disabilities and cerebral palsy, and even death. Cocaine-exposed babies also tend to have smaller heads, which generally reflect smaller brains and an increased risk of learning problems (8).
There are few studies on the risks of these drugs during pregnancy. Babies of mothers who used PCP in pregnancy may have withdrawal symptoms (7, 18). Babies exposed before birth to PCP or ketamine may be at increased risk of learning and behavioral problems (7, 18). There have been occasional reports of birth defects in babies of women who used LSD during pregnancy, but it is not known whether or not the drug contributed to the defects (7).
Birth defects and other problems caused by illicit drugs are completely preventable. The March of Dimes advises women who use illicit drugs to stop before they become pregnant or to delay pregnancy until they believe they can avoid the drug completely throughout pregnancy. The March of Dimes also encourages pregnant women who use illicit drugs (with the exception of heroin) to stop using the drug immediately, because of the harm continued drug use may cause. Women who use heroin should consult their health care provider or a drug treatment center about methadone treatment.
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