Drug use in pregnancy requires special considerations, since medications have the potential to affect the developing fetus. In addition, pregnancy alters pharmacokinetic parameters of some medications, resulting in a need for dosage adjustment. Drug regimens for management of acute and chronic disorders in pregnancy should be tailored to optimize the health of the mother while minimizing risk to the fetus. After delivery, measures should be taken to minimize drug exposure to the breastfeeding infant. Pharmacists can play a key role in maximizing the safe and effective use of medications during pregnancy and lactation.
Preconception care should be discussed with all women of childbearing age. The goal of preconception care is to minimize poor pregnancy, fetal/infant and maternal outcomes. Elements of preconception care include supplementation, dietary considerations, immunizations, and optimization of control of chronic diseases.
Vitamin and Mineral Supplementation
Folic acid deficiency is a major cause of neural tubal defects (NTDs), and adequate intake of folic acid can reduce the incidence of NTDs by 50% to 70%. Most women of childbearing age should be advised to take a multivitamin (MVI) with 400 μg of folic acid daily. Higher doses (4 to 5 mg daily) are required for women with an increased risk of delivering a child with NTDs (eg, women taking antiepileptic medications). Initiation of supplementation should be at least 1 month before conception and continue throughout the first trimester.
Multivitamins offer additional benefit in meeting calcium (1000-1300 mg) and iron requirements. Calcium is important for bone health for the mother and fetus. Additional calcium supplementation with calcium carbonate or citrate may be needed if MVI and dietary intake is insufficient. The CDC recommends supplementation with 27 to 30 mg/day of elemental iron to support the increased demands of pregnancy.
Caffeine consumption may result in infertility, miscarriage, and low birth weight. Low to moderate amounts of caffeine (<200 mg/day) appear to be safe. Seafood contains long-chain omega-3 polyunsaturated fatty acids and mercury. Fatty acids are beneficial to the central nervous system, but mercury can lead to birth defects. It is recommended to limit intake to 12 oz of seafood per week with lower mercury content. Alcohol consumption may adversely affect fertility, contribute to complications during pregnancy, and cause fetal alcohol syndrome (physical, behavioral, and cognitive abnormalities) in infants. No level of alcohol consumption is considered safe during pregnancy.
Ideally, immunizations should be up-to-date before conception. Inactivated vaccines are safe during pregnancy and live vaccines (varicella, MMR) should be avoided due to a theoretical risk of transmission to the fetus. Influenza is associated with high morbidity and mortality, and every pregnant woman should receive the inactivated influenza vaccine. The CDC also recommends Tdap (tetanus, diphtheria, pertussis vaccine) with each pregnancy, ideally given at 27 to 36 weeks gestation, regardless of the interval between pregnancies.
TERATOGENIC EFFECTS OF DRUGS
Developmental toxicity may occur when an exposure coincides with a critical period of fetal development. The most critical time of fetal development is in the first 8 weeks of pregnancy. The goal of drug use during pregnancy is to treat conditions as necessary, while minimizing the risk to the fetus.
Risk of drug therapy to the fetus is assessed ...