Introduction

Substance abuse is widely prevalent in our society and women in their child-bearing years are not immune to this epidemic. In addition to the many problems substance abuse causes for these women it also places the children they are carrying at risk for lifelong sequelae. Virtually all pregnant women are exposed to drugs in some form (such as acetaminophen, iron, multivitamins, and antimicrobials) and it is estimated that approximately 10% are exposed to illicit substances. The purpose of this chapter will be to describe the fetal and neonatal effects of various sensorium-altering licit and illicit substances ingested by pregnant women.

Drug distribution in pregnancy

Before discussing the various substances that may be ingested, it is important to understand general principles of drug distribution during pregnancy, including the roles of the placenta and breast in biotransformation and secretion. Drugs that are abused are capable of easily and rapidly entering the nervous system. The characteristics that favor transport of a drug across the lipoprotein barriers between the circulation and the central and peripheral nervous systems include high lipid solubility, minimal ionization at physiologic pH, low proteinbinding, and low molecular weight. High lipid solubility may result in storage of such substances in maternal body fat with subsequent release and transfer into fetal lipid stores during pregnancy. These same characteristics also enable drugs to cross the placenta readily and enter the fetal circulation.