Possible Effects of Selected Substances on the Fetus
Alcohol and other drug use is often associated with poor nutrition. This association can result in serious health consequences for pregnant, substance-using women and their infants. Scarce financial resources and a lack of knowledge about the elements of good nutrition may further compound these effects. The following information describes the possible effects of maternal use of cigarettes, alcohol, marijuana, heroin, and cocaine. It is possible that infants will show no adverse effects from maternal use of these or other drugs. The use of other drugs in addition to those listed below, as well as polydrug use, may also impact the health of women and their infants. There are clinical recommendations for improved nutrition and guidelines for nutritional assessment and education.

Cigarette Smoking

• Possible effects of maternal smoking during pregnancy. Decreased birth weight is the most consistently observed effect of maternal smoking on infants. This decrease in infant birth weight is on average 200 g. A recent review of the literature on the determinants of low birth weight has, like previous reviews, concluded that cigarette smoking is by far the single most important modifiable factor responsible for fetal growth retardation in developed countries.
• Possible nutrition-related effects of smoking. Cigarette smoking may affect maternal nutrition and, consequently, fetal nutrition, in two important ways: (1) the increased metabolic rate in smokers can lead to lower availability of calories; and, (2) the exposure to tobacco may increase iron requirements and decrease the availability of certain nutrients such as vitamin B12, amino acids, vitamin C, folate, and zinc. In smokers, uteroplacental blood flow restricts nutrient and oxygen flow to the fetus.

Alcohol

• Possible effects of excessive maternal alcohol consumption during pregnancy. Alcohol is now recognized as a potent teratogen. Infants of mothers who consume excessive amounts of alcohol during pregnancy may suffer from Fetal Alcohol Syndrome or Fetal Alcohol Effects.
• Possible nutrition-related effects of alcohol consumption. Alcohol consumption may be related to decreased dietary intake, impaired metabolism and absorption of nutrients, and altered nutrient activation and utilization. Interactions between alcohol and deficiencies of such nutrients as protein and zinc may also play a role in the etiology of alcohol-related effects on the fetus.
• Although there is no convincing evidence that nutritional supplementation will counteract the adverse effects of alcohol, standard prenatal vitamins plus folate, B12, and iron supplementation should be prescribed. However, since alcohol abuse has clearly been shown to be detrimental to the fetus, nutritional supplementation should not replace efforts to encourage women to limit or eliminate alcohol intake during pregnancy.

Marijuana

• The marijuana of the 1990s is very different from the drug that was available in the 1960s. Today there are more THC’s (tetrahydrocannabinols) in marijuana because of plant hybridization.
• Possible effects of maternal marijuana use during pregnancy. Decreased birth weight and body length are the most commonly noted effects among infants of mothers who use marijuana during pregnancy.
• Possible nutrition-related effects of marijuana use. There are conflicting study results on the possible nutrition-related effects of marijuana use. Some studies indicate weight gain by infants, other studies show less weight gain, while still others show no difference between infants whose mothers used marijuana and infants whose mothers did not use the drug.

Heroin

• Possible effects of maternal use of heroin during pregnancy. Decreased birth weight, prematurity, and intrauterine growth retardation and neonatal withdrawals are among the effects on the fetus of maternal heroin use during pregnancy. Medical complications from the use of dirty needles may also ensue, such as abscesses, bacterial endocarditis, and hepatitis in the mother. There is a risk of mother to child transmission of viruses such as hepatitis C or HIV if the mother is infected.
• Possible nutrition-related effects of heroin use. These effects include poor nourishment, with vitamin deficiencies, iron deficiency anemia, and folic acid deficiency anemia. Many of the effects on pregnancy and the fetus can be addressed in a comprehensive methadone maintenance treatment program.

Cocaine

• Possible effects of maternal use of cocaine during pregnancy. Spontaneous abortion, intrauterine growth retardation, neonatal withdrawals, premature labor, and abruptio placentae are among the effects of maternal use of cocaine.
• Possible nutrition-related effects of cocaine use. As is true for marijuana, little is known about the nutrition-related effects of cocaine use. Cocaine's vasoconstrictive ability may lead to fetal hypoxia and reduced nutritional supply to the fetus. Since cocaine, like amphetamines, acts as an appetite suppressant, an inadequate maternal diet may play a role in retarding growth in fetuses of cocaine abusers.

Clinical Recommendations

• Prevention and intervention. The highest priority should be given to efforts to prevent or stop alcohol and other drug use by pregnant women. There is clear evidence that cigarette smoking and alcohol and other drug use adversely affect the health of the mother and fetus.
• Nutrition counselling and intervention. Since nutritional deficiencies can be expected, especially among heavy abusers of alcohol and other drugs, diet counselling, referral to a social worker, and other intervention strategies to improve food intake are recommended.
• Multivitamin-mineral supplementation. Because heavy abusers of alcohol and other drugs may have difficulty in taking the steps needed to improve their dietary intake, the use of multivitamin-mineral supplements is recommended.