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For the chapter in the Wells Handbook, please go to Chapter 32. Pregnancy and Lactation.



  • image Complex physiology surrounds the process of fertilization and pregnancy progression.

  • image Drug characteristics and physiologic changes modify drug pharmacokinetics during pregnancy, including changes in absorption, protein binding, distribution, and elimination, requiring individualized drug selection and dosing.

  • image Although drug-induced teratogenicity is a serious concern during pregnancy, most drugs required by pregnant women can be used safely. Informed selection of drug therapy is essential.

  • image Healthcare practitioners must know where to find and how to evaluate evidence related to the safety of drugs used during pregnancy and lactation.

  • image Health issues influenced by pregnancy, such as nausea and vomiting, can be treated safely and effectively with nonpharmacologic treatment or carefully selected drug therapy.

  • image Some acute and chronic illnesses pose additional risks during pregnancy, requiring treatment with appropriately selected and monitored drug therapies to avoid harm to the woman and the fetus.

  • image Management of the pregnant woman during the peripartum period not only can encompass uncomplicated pregnancies/deliveries, but can also include a wide variety of potential complications that require use of evidence-based treatments to maximize positive maternal and neonatal outcomes.

  • image Understanding the physiology of lactation and pharmacokinetic factors affecting drug distribution, metabolism, and elimination can assist the clinician in selecting safe and effective medications during lactation.

A controversial and emotionally charged subject because of medicolegal and ethical implications, drug use in pregnancy and lactation is a topic often underemphasized in the education of health professionals. Clinicians are responsible for ensuring safe and effective therapy before conception, during pregnancy and parturition, and after delivery. Active patient participation is essential. Optimal treatments of illnesses during pregnancy sometimes differ from those used in the nonpregnant patient.

In many cases, medication dosing recommendations for acute or chronic illnesses in pregnant women are the same as for the general population. However, some cases require different dosing and selection of medications. Principles of drug use during lactation, although similar, are not the same as those applicable during pregnancy.


image Fertilization and progression of pregnancy are complex, resulting in survival of only approximately 50% of embryos.1 Because most losses occur early, usually in the first 2 weeks after fertilization, many women do not realize they were pregnant. Spontaneous loss of pregnancy later in gestation occurs in about 15% of pregnancies that survive the first 2 weeks after fertilization.2

Fertilization occurs when a sperm attaches to the outer protein layer of the egg, the zona pellucida, and renders the egg nonresponsive to other sperm.3 The attached sperm releases enzymes that allow the sperm to fully penetrate the zona pellucida and contact the egg’s cell membrane. The membranes of the sperm and egg then combine to create a new, single cell ...

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