Pregnancy and drug use

DEFINITION: Drug abuse during pregnancy frequently leads to spontaneous abortion, premature birth, stillbirth, low birth weight infants, and an increased risk of sudden infant death syndrome. Congenital disorders caused by drug abuse during pregnancy are rare, however. Drugs considered to have abuse potential during pregnancy include marijuana, cocaine, heroin, hallucinogens, methamphetamine, and prescription pain medications.

Drug Use During Pregnancy

According to the National Institute on Drug Use's Substance Use in Women Research Report, around 5 percent of pregnant women use one or more addictive substances each year.

Certain factors in the lives of women who use drugs contribute to their reluctance to seek help, obtain prenatal care, or stop using drugs during pregnancy. Many women who exhibit a pattern of drug use have mental, social, and financial problems. These situations contribute to an overall unhealthy routine that may include smoking, poor diet, stress, violence, and unpredictable living conditions, resulting in adverse pregnancy outcomes.

Women with addictions to other substances are much more likely to smoke cigarettes and use intravenous drugs during pregnancy, potentially exposing themselves to blood-borne infections like hepatitis C, human immunodeficiency virus (HIV), and Zika. The high rates of anxiety, depression, and personality disorders in women who abuse drugs contribute to a high rate of relapse among those who attempt to discontinue drug use while pregnant.

Women who abuse drugs may fail to obtain prenatal care for several reasons. For example, amenorrhea is a common side effect of drug abuse, so a woman may not realize she is pregnant. Drug use can be particularly risky to the fetus during the first eight weeks of pregnancy, a critical period of fetal development. Drug addiction also may lead to forgotten or missed appointments or to a lack of concern regarding the health of the fetus. Women who abuse drugs also endanger their own health through unhealthy lifestyles and relationships that may involve physical abuse, which also risks harm to the fetus.

Cocaine

The 1980s witnessed a significant increase in the use of cocaine and crack cocaine in the United States. Cocaine remains a serious public health issue in the United States, and most women who use cocaine are of childbearing age. When a pregnant woman uses cocaine, the drug crosses the blood-brain barrier and the placenta, becoming readily available to the developing fetus. Animal models have shown that cocaine interferes with fetal brain development because it interacts with neurotransmitters and affects gene expression, but the mechanisms for this are unknown. Children exposed to cocaine prenatally have demonstrated deficits in attention span and impulse control, which may be attributed to the effects of cocaine on areas of the brain regulating these functions.

Cocaine is known to be a vasoconstrictor and may contribute to spontaneous abortion and low birth weight (under 2,500 grams or 5 pounds, 8 ounces) from a lack of blood flow to the fetus. Cocaine use during pregnancy, especially crack cocaine, has been linked to the malformation of arms, legs, and internal organs because of this vasoconstriction effect during fetal development. Lack of blood flow across the placenta also prevents the transport of oxygen and nutrients to the fetus. Infants born to women with cocaine addictions also are more likely to be hospitalized in a neonatal intensive care unit.

Infants are also affected indirectly by their mother’s cocaine use through the effects that use has on the area of the brain that controls maternal behavior. Cocaine disrupts the pathways in the brain that control maternal-infant bonding behavior and disrupts the production of oxytocin, a hormone that is key to triggering response behaviors in mothers.

Other Substances

In addition to cocaine, other frequently misused substances, such as methamphetamine, marijuana, hallucinogens, and opiates, increase the risk of premature labor and low birth weights. Methamphetamine use has grown substantially in the United States and worldwide in the twenty-first century. Studies continue to emerge outlining the dangerous impact of prenatal meth use on the fetus, but scientists agree that meth is linked to neurotoxicity, cardiovascular toxicity, and hepatotoxicity.

It is known that methamphetamine interacts with biochemical transporters in the brain and is transported directly into cells. Once inside nerve cells, methamphetamine disrupts the release and metabolism of neurotransmitter molecules in the brain, impairing the development of the neurotransmitter system. Methamphetamine is a vasoconstrictor, similar to cocaine, and can have the same effect on the fetus through lack of blood flow.

Magnetic resonance imaging studies of children exposed to methamphetamine in utero have revealed abnormal brain structure in association with neurological developmental deficiencies. Newborn babies prenatally exposed to methamphetamine are usually underweight and have shown similar neurological effects as those exposed to cocaine. Animal models have demonstrated learning deficiencies, behavioral problems, and hyperactivity.

Heroin is a short-acting opiate that, with repeated use and withdrawal, can cause muscle contractions, leading to premature labor. However, no studies have shown that heroin use during pregnancy causes central nervous system damage in the developing fetus. Opiates cross the placenta, so opiate abusers may give birth to newborns addicted to drugs who must subsequently undergo withdrawal. These newborns experience irritability, central nervous system difficulties, gastrointestinal disorders, and respiratory symptoms for up to eight days after birth. As in the case of cocaine, it is difficult to determine if these symptoms are caused by the mother’s heroin use or are consequences of other factors associated with the mother’s lifestyle.

By the end of the second decade of the twenty-first century, as an increasing number of states had made or proposed changes to laws regarding recreational and medicinal marijuana use, researchers were continuing to study the potential effects of prenatal use of marijuana. In early 2020, a study published in the Journal of Perinatology conducted by researchers affiliated with institutions in Iowa and Minnesota found evidence supporting a link between marijuana use during pregnancy and the growth of the fetus. Particularly, their findings indicated that babies born to women who smoke marijuana during pregnancy may have an increased risk of being born small-for-gestational age, which is considered to be below the tenth percentile.

Alcohol, a psychotropic central nervous system depressant, is commonly considered its own category and not thought of as a drug. Still, its negative impact on fetal development matches that of drugs like cocaine and Xanax. Alcohol is absorbed in the blood and passes from mother to fetus through the umbilical cord. Consistent alcohol consumption during pregnancy may result in fetal alcohol spectrum disorders (FASDs). Symptoms of FASDs are life-long and include learning disabilities, speech delay, diminished attention, poor memory, low IQ, and problems with vision and hearing or with the heart, kidney, or bones. Drinking alcohol while breastfeeding can also be dangerous.

Remedial Actions

It is difficult to attribute specific fetal deficiencies to illicit drug use because of the many other confounding factors in the woman’s life. These factors include smoking and poor nutrition, both of which may adversely affect the pregnancy.

The American College of Obstetricians and Gynecologists advocates for screening all women as part of their regular prenatal visits. Several screening tools are available to indicate a woman's potential for substance use disorders during pregnancy. For women under twenty-seven, CRAFFT is often used, and NIDA Quick Screen and 4Ps are suitable measures for all pregnant women. The TACER-3 is a screening tool specifically for prenatal alcohol abuse.

Residential treatment during pregnancy has demonstrated positive outcomes, but it is unclear if this outcome is from stabilization of the drug use or from an overall healthier lifestyle. Studies have shown that women with substance use disorder who receive early intervention and extensive prenatal care and supervision can have pregnancy outcomes equivalent to women who do not use drugs. Comprehensive prenatal care can substantially reduce the risk of premature labor and low birth weight infants.

It is recommended that pregnant women stop using cocaine during pregnancy, but the cocaine must be reduced in a measured fashion to avoid side effects, such as maternal seizures. Methadone treatment has been found to stabilize opiate abusers during pregnancy by allowing women to gradually diminish opiate abuse through the pregnancy without the repeated use and withdrawal of heroin. The effect of drug abuse on infant mortality remains to be studied and delineated, but sudden infant death syndrome, premature birth, and stillborn birth all increase in frequency with drug use.

Bibliography

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Li, Jia-Hao, et al. “The Adverse Effects of Prenatal METH Exposure on the Offspring: A Review.” Frontiers in Pharmacology, vol. 12, 14 Jul. 2021, doi:10.3389/fphar.2021.715176.

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