Substance abuse during pregnancy poses a threat to the health and well-being of both the mother and her unborn child. It is difficult to know exactly how many women abuse alcohol and drugs during their pregnancies, but the problem is clearly of concerning size. About 15% of women who present for prenatal care have been shown to have a positive urine test for one or more of the following: alcohol, marijuana, cocaine, and opiates (such as heroin). This is worrisome not only because almost every substance of abuse freely crosses the placenta into the fetus but also because of the risky behaviors which can be associated with substance abuse, including unsafe sex, exchanging sex for drugs and money, and engaging in physically unsafe behavior. Although many of the substances described below may cause fetal death, this article takes a broader look at the effects of both licit and illicit substances on a woman and her fetus. This article summarizes what is known about the effects of certain substances during pregnancy in the hope that education will help women to understand the risks of using substances during pregnancy and will help them to choose to abstain while they are pregnant.
Tobacco: Tobacco smoke is a highly complex substance containing many possibly harmful ingredients including nicotine, tar, carbon monoxide, and cyanide. All of these appear to contribute to the health problems affecting mothers who smoke, including respiratory illnesses, peptic ulcer disease, esophageal reflux, and in the long term, cancer. Nicotine is particularly problematic during pregnancy because it tends to make blood vessels constrict which causes there to be less blood flow to the placenta which translates into less oxygen and nutrients for the fetus. In addition to decreasing blood flow, smoking can lead to a complication called placental abruption, a condition in which the placenta detaches from the wall of the uterus before the fetus is ready to be born. One in 500 cases of severe abruption leads to fetal death. In general, smoking is associated with an increased frequency of miscarriage with the risk of miscarriage is increased 1.2 fold for every 10 cigarettes smoked. A report by the Surgeon General in 1983 estimated that 4600 infants died each year in the United States as a result of smoking during pregnancy. Babies of smokers also tend to be born prematurely and to have lower birth weights with birthweight reduction being directly related to the number of cigarettes smoked each day. Increased rates of neonatal death and of the sudden infant death syndrome (SIDS) have also been observed. The long-term effects of smoking are still under investigation, but smoking during pregnancy has been associated with impaired growth after birth, impaired intellectual development, and behavioral disorders including hyperactivity and attention deficit disorders. Alcohol: Alcohol use during pregnancy is a significant problem: it has been estimated that as many as 1 in 300 infants are born with some stigmata of fetal alcohol exposure. The most well described stigmata are part of the Fetal Alcohol Syndrome (FAS) which includes 1) prenatal and postnatal growth retardation, 2) central nervous system involvement, and 3) characteristic facial features. The central nervous system effects include tremulousness, poor suckling, abnormal muscle tone, hyperactivity, attention deficit, and mental retardation. The typical facial features include microcephaly (a small head), a thin upper lip, a short upturned nose, a flattened nasal bridge (upper portion of the nose), and general underdevelopment of the midface area. Drinking patterns vary among women, and it appears that heavier drinking is associated with more congenital problems. However, it is important to know that no safe level of alcohol intake during pregnancy has ever been defined. Both binge drinking and daily drinking increase the risk both of fetal abnormalities, such as in the FAS, and of fetal death. Alcohol use during pregnancy is associated with an increased incidence of second trimester miscarriage in moderate to heavy drinkers. Abruption of the placenta and breech presentation also appear to be more common in fetuses with the fetal alcohol syndrome. Other fetal defects which may be associated with alcohol exposure include congenital heart defects, brain abnormalities, spinal bifida, limb defects, urinary tract defects, and genital defects.
Marijuana Marijuana is the most commonly used illicit substance in the United States, and it is the most common recreational drug used during pregnancy. It is important to know that the psychoactive ingredient in marijuana, 1,9-tetrahydrocannabinol (THC), is a substance which accumulates in fat. THC is eventually broken down by the liver before being excreted, but it may stay in fat tissue for days. Thus, the effects of using marijuana may persist for some time. Marijuana has multiple effects on the mother including producing tachycardia (a fast heart rate), exercise intolerance, bronchitis (inflammation of the airways in the lungs), sinusitis (inflammation of the sinuses), and pharyngitis (inflammation of the back of the mouth and throat). The effects of marijuana on the fetus are the subject of some debate. There are reports in the literature of decreased body length, intrauterine growth retardation, neurobehavioral effects, and an increased incidence of prematurity. These findings, however, have not been consistent in all studies so there are no firm conclusions about the effects of marijuana on a fetus. Cocaine Cocaine acts as a potent stimulator of the brain which produces the euphoria experienced by the user, and it has been estimated that 10 percent of the obstetric population uses cocaine. Cocaine's other effects, however, can be quite dangerous. The mother may experience a number of serious side effects including a fast heart rate, dangerously high blood pressure, a heart attack, an irregular heart beat, muscle twitching, seizures, a stroke, increased body temperature, and even sudden death. The effects of these conditions on the fetus can be dramatic and may be fatal. Placental abruption is seen in up to 8% of cocaine abusers. Miscarriages during the first trimester are estimated to occur at a rate approaching 40%. Babies of cocaine abusers tend to have low birth weights, intrauterine growth retardation, and are more likely to be premature. Cocaine, like nicotine, tends to constrict blood vessels, sometimes with dire consequences. Constriction of blood vessels is thought to be responsible for certain fetal abnormalities associated with cocaine abuse including failure to form part of the intestines and failure to form the limbs properly. Congenital heart defects and urinary tract abnormalities have also been observed. The effects on the fetus' central nervous system varies from major disruptive brain anomalies to the disordered behaviors seen in newborns. Newborns tend to have depressed interactive behavior and have difficulty organizing their responses to the outside world. Research is currently underway to study the long-term effects of cocaine use during pregnancy. Opiates Heroin and methadone are the most frequently encountered drugs in this class used during pregnancy. Although neither causes congenital abnormalities, they pose a significant threat not only because use of heroin involves needles and thus may increase the risk for HIV infection but also because withdrawal can be fatal to the fetus. Problems with the mother may encounter from using heroin include overdose, skin and subcutaneous tissue infections, inflammation of the veins used for injection, endocarditis (infection of the tissues of the heart), and urinary tract infection. Also, there is an increased incidence of inflammation and infection of the placenta and the uterus. Opiate use is also associated with an increased risk of premature labor and delivery, low birth weight, fetal distress, and neonatal infections. Withdrawal in the mother can cause agitation, lacrimation (tearing), rhinorrhea (runny nose), yawning, perspiration, abdominal and uterine cramps, diarrhea, and myalgias (muscle aches). Withdrawal in mother may be fatal to the fetus because it results in hyperactivity, hypoxia (lack of oxygen to the fetus), and meconium (passage of the fetus' first bowel movement while still in the uterus which is a sign that the fetus is in distress). All babies born to mothers using heroin will be addicted to the drug and 80% of those born to mothers on methadone will be addicted to opiates. The addicted babies will undergo the Neonatal Withdrawal Syndrome. The symptoms begin in the first 12-24 hours after birth and include high-pitched crying, frantic fist sucking, frantic searching for food, and tremulousness. The baby can have seizures, can display a disrupted sleep-wake cycle, and can have rigid muscles. The long-term effects of opiate use have yet to be defined. In terms of using heroin versus methadone, methadone is thought to be better because the levels of the drug are more constant and there is much less likelihood that the mother will withdraw.
Amphetamines Amphetamines are central nervous system stimulants with effects on the brain similar to cocaine. Tolerance develops with use leading the user to need more to achieve the same euphoric feelings. Amphetamines may cause the user to be hyperactive, to be paranoid, to hallucinate, to suffer insomnia, and to be malnourished secondary to a decreased appetite. These drugs can be used intravenously, and this may increase the risk for HIV infection. Very little is known about what amphetamines do to the fetus. Although no defined set of congenital anomalies exists, there is some indication that amphetamine use my be associated with placental abruption, prematurity, and low birth weight. Hallucinogens The most commonly used hallucinogens are lysergic acid diethlamide (LSD, "acid") and phencyclidine (PCP, "angel dust"). The effects on the mother are significant because users tend to put themselves in dangerous situations which can lead to harm of the mother and her fetus. Users can become violent which may lead to direct trauma. The direct effects of these substances on the fetus are not well defined. There are some reports in the literature suggesting that use of hallucinogens is associated with decreased birth weight and decreased head circumference, but these findings may be attributable to environmental factors. Neonates, nonetheless, can withdraw from hallucinogens with such symptoms as tremors, jitteriness, and irritability. The long-term effects are still being investigated but may involve developmental delays. Conclusions Using drugs and alcohol during pregnancy can cause a variety of problems for both the mother and her fetus ranging from malnutrition in the mother to major congenital abnormalities involving vital structures such as the heart or brain. There are a few points to remember. There is no safe level of use of any of the substances discussed above. Even in a substance of abuse does not have an obvious syndrome of abnormalities associated, it may be affecting the fetus in ways that will not become apparent until the baby has reached school age or adulthood. Also, it is often the environment in which substances are abused and the fact that when one substance is abused it is more likely that many substances will be abused that poses the greatest threat to the mother and the fetus. And finally, the time to deal with substance abuse is before pregnancy begins because many of the vital organs are formed during the first 60 days of pregnancy, before some women are even aware that they are pregnant. References: 5. Bell, GL and Lau, K: "Perinatal and Neonatal Issues of Substance Abuse." Pediatric Clinics of North America 42 (2): 261-281, 1995.
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