Teratogenesis: A Review of the Basic Principles with a Discussion of Selected Agents: Part III

Abstract

Before a woman realizes she is pregnant, a large amount of development has occurred in the embryo. If she consumes a drug during her pregnancy, the possibility exists that the drug could harm the fetus. The most important variable is timing, with the fetus showing the highest degree of susceptibility during the first trimester of gestation. This article presents data on the relative time a pregnancy test becomes positive as compared to fetal development; passage of drugs across the placenta; placental and fetal drug metabolism; and the availability of teratogenic information to health professionals. Teratogenic effects of specific substances or classes of substances are discussed, including alcohol, analgesics, antibiotics, anticoagulants, anticonvulsants, antithyroid/thyroid drugs, various environmental agents, and paternal drug exposure.