Drugs, Birth, and Ethics

Abstract

When fetal organs are developing, exposure to many drugs and other substances may produce behavioral, neurological, and structural changes. These agents are called teratogens when they produce physical changes and behavioral teratogens when they produce behavioral changes with or without accompanying physical changes. Figure 1 shows, for a rat fetus, the limited periods during embryogenesis when it is susceptible to physical deformity and the longer period, preceding and following birth, when the animal is vulnerable to central nervous system damage. In human beings, the period of vulnerability to central nervous system damage from exposure to drugs and chemicals lasts much longer. Even after birth, important areas of brain are growing and differentiating at a rapid rate and are still, therefore, especially vulnerable to damage. It has been estimated that the “growth spurt” in the cerebellum lasts for about 18 months, and that in the hippocampus, for about 4.5 years.