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Effects of toxic substances on pregnancy and the fetus
Last reviewed: 04.07.2025
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Alcohol and illicit drugs are toxic to the placenta and developing fetus and can cause congenital syndromes as well as withdrawal symptoms.
While the use of certain toxic substances does not constitute illegal behavior on the part of the mother, the use of some does. In all cases, the home environment should be assessed to determine whether adequate care for the baby after discharge will be possible. With the help of family, friends, and visiting nurses, the mother may be able to care for her baby. If not, foster care or an alternative care plan may be the best option.
Alcohol and pregnancy
Exposure to alcohol during pregnancy can cause fetal alcohol syndrome (FAS), a diverse combination of physical and cognitive impairment. At birth, infants with FAS can be identified by poor physical stature and a typical set of facial features, including microcephaly, microphthalmia, short palpebral slits, epicanthal folds, small or flat midface, flat and elongated nasal filter, thin upper lip, and small chin. Abnormal dermatoglyphics, cardiac defects, and joint contractures may also be present. The most serious manifestation is profound mental retardation, thought to be a teratogenic effect of alcohol in the large number of children with mental retardation born to alcoholic mothers; FAS may be the most common cause of nonfamilial mental retardation. No single physical or cognitive feature is pathognomonic; the less alcohol is consumed, the less severe the clinical manifestations in the child, and diagnosis of mild degrees may be difficult. It is often difficult to distinguish the effects of alcohol on the developing fetus from the effects of other substances (e.g. tobacco, drugs) and other factors (e.g. poor nutrition, inadequate medical care, violence), to which women who abuse alcohol are particularly susceptible.
The diagnosis is made in infants with characteristic features who were born to chronic alcoholics who abused alcohol during pregnancy.
Because it is not known when during pregnancy alcohol is most likely to cause harm to the fetus or whether there is a minimum level of alcohol consumption that is completely safe, pregnant women should be advised to avoid alcohol completely. Siblings of infants diagnosed with FAS should be evaluated for signs of fetal alcohol syndrome.
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Barbiturates and pregnancy
Long-term maternal abuse of barbiturates may cause a neonatal withdrawal syndrome characterized by restlessness, agitation, and irritability that often does not develop until 7 to 10 days after birth, before the infant is discharged home. Sedation with phenobarbital at a dose of 0.75 to 1.5 mg/kg orally or intramuscularly every 6 hours, tapered over several days or weeks depending on the duration of symptoms, may be required.
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Cocaine and pregnancy
Cocaine inhibits the reuptake of the neurotransmitters norepinephrine and epinephrine; it crosses the placenta and causes vasoconstriction and hypertension in the fetus. Cocaine abuse during pregnancy is associated with an increased risk of placental abruption and spontaneous abortion, possibly caused by decreased maternal blood flow to the placental vessels; abruption may also result in intrauterine fetal death or neurologic damage if the fetus survives. Infants of cocaine-using mothers have low birth weight, reduced length and head circumference, and low Apgar scores. Cerebral infarctions may develop, as may rare anomalies associated with prenatal cocaine use, including limb amputations; gastrointestinal malformations including abdominal muscle separation; and intestinal atresia or necrosis. All are caused by vascular rupture, presumably secondary to local ischemia due to the intense vasoconstriction of fetal arteries caused by cocaine. In addition, there are signs of mild neurobehavioral effects of cocaine, including decreased attention and anxiety, lower IQ, and impaired growth and fine motor skills.
Some newborns may experience withdrawal symptoms if the mother used cocaine shortly before birth, but symptoms are less common and less severe than those of opioid withdrawal, and treatment is the same.
Opioids and pregnancy
Opioid exposure may cause withdrawal at birth. The newborn of a woman who abuses opioids should be observed for withdrawal symptoms, which usually occur within 72 hours after birth. Characteristic withdrawal symptoms include restlessness, excitability, hypertonicity, vomiting, diarrhea, sweating, seizures, and hyperventilation, leading to respiratory alkalosis. Prenatal benzodiazepine exposure may cause similar effects.
Treatment of mild withdrawal symptoms includes swaddling and sedation for a few days to reduce physical hyperactivity and frequent feedings to reduce restlessness. With patience, most problems resolve within a week. Severe symptoms are controlled with 25-fold dilution of opium tincture (which contains 10 mg/ml) in water, given at 2 drops (0.1 ml)/kg PO every 4 hours. The dose may be increased by 0.1 ml/kg every 4 hours if necessary. Withdrawal symptoms can also be controlled with phenobarbital at a dose of 0.75-1.5 mg/kg PO every 6 hours. The dose is gradually reduced and treatment stopped after a few days or weeks when symptoms resolve.
The incidence of SWS is higher in infants born to women using opioids, but is still lower than 10/1000 infants, so routine use of home cardiorespiratory monitors is not recommended in these infants.