Cigarette smoking is the most common addiction among pregnant women. Carbon monoxide and nicotine in cigarettes cause hypoxia and vasoconstriction, increasing risk of the following:
Spontaneous abortion (fetal loss or delivery < 20 weeks)
Placental abruption (abruptio placentae)
Neonates whose mothers smoke are also more likely to have anencephaly, congenital heart defects, orofacial clefts, sudden infant death syndrome, deficiencies in physical growth and intelligence, and behavioral problems. Smoking cessation or limitation reduces risks.
Exposure to secondhand smoke may similarly harm the fetus.
Alcohol is the most commonly used teratogen. Drinking alcohol during pregnancy increases risk of spontaneous abortion. Risk is probably related to amount of alcohol consumed, but no amount is known to be risk-free. Regular drinking decreases birth weight by about 1 to 1.3 kg. Binge drinking in particular, possibly as little as 45 mL of pure alcohol (equivalent to about 3 drinks) a day, can cause fetal alcohol syndrome. This syndrome occurs in 2.2/1000 live births; it includes fetal growth restriction, facial and cardiovascular defects, and neurologic dysfunction. It is a leading cause of intellectual disability and can cause neonatal death due to failure to thrive.
Stimulants such as cocaine or methamphetamine have indirect fetal risks (eg, maternal stroke or death during pregnancy). Their use probably also results in fetal vasoconstriction and hypoxia. Repeated use increases risk of the following:
Congenital malformations (eg, central nervous system, genitourinary, and skeletal malformations; isolated atresias)
Although the main metabolite of cannabis can cross the placenta, recreational use of marijuana use does not consistently appear to increase risk of congenital malformations or fetal growth restriction. Marijuana use during pregnancy has been linked to adverse pregnancy outcomes including small-for-gestational-age, preterm labor, and infant neurodevelopmental and behavioral problems. A trend toward easier recreational access to and broader use of marijuana in several states may lead to an improved understanding of marijuana's effects over time.
Bath salts refers to a group of designer illicit drugs made from a variety of amphetamine-like substances; these drugs are being increasingly used during pregnancy. Although effects are poorly understood, fetal vasoconstriction and hypoxia are likely, and there is a risk of stillbirth, placental abruption, and possibly congenital malformations.
Hallucinogens may, depending on the drug, increase risk of the following:
Withdrawal syndrome in the fetus or neonate
Hallucinogens include methylenedioxymethamphetamine (MDMA, or Ecstasy), rohypnol, ketamine, methamphetamine, and LSD (lysergic acid diethylamide).
Opioids (eg, heroin, methadone, morphine) readily cross the placenta and thus may result in opioid dependence in the fetus. The neonate may have withdrawal symptoms 6 hours to 8 days after birth. However, use of opioids rarely results in congenital malformations. Opioid partial agonist therapy, such as buprenorphine, may be associated with a lower risk for neonatal withdrawal versus methadone and is being increasingly used for patients with opioid dependence during pregnancy.
Use of opioids during pregnancy increases the risk of pregnancy complications, such as
Abnormal fetal presentation
Heroin increases the risk of having a small-for-gestational-age infant.
Whether consuming caffeine in large amounts can increase perinatal risk is unclear. Consuming caffeine in small amounts (eg, 1 cup of coffee/day) appears to pose little or no risk to the fetus, but some data, which did not account for tobacco or alcohol use, suggest that consuming large amounts (> 7 cups of coffee/day) increases risk of stillbirths, preterm deliveries, low birth weight, and spontaneous abortions. Decaffeinated beverages theoretically pose little risk to the fetus.
Use of aspartame (a dietary sugar substitute) during pregnancy is often questioned. The most common metabolite of aspartame, phenylalanine, is concentrated in the fetus by active placental transport; toxic levels may cause intellectual disability. However, when ingestion is within the usual range, fetal phenylalanine levels are far below toxic levels. Thus, moderate ingestion of aspartame (eg, no more than 1 liter of diet soda per day) during pregnancy appears to pose little risk of fetal toxicity. However, in pregnant women with phenylketonuria, intake of phenylalanine and thus aspartame is prohibited.
