No area within the field of pharmacogenomics generates greater excitement and potential for altering the way we practice medicine than fetal and neonatal pharmacogenomics. Though only in its infancy (no pun intended), this area that lies at the crossroads of perinatology, neonatology, pharmacology, and genetics will undoubtedly not only shape the way we diagnose and treat diseases of expectant mothers and their infants, but also improve our overall understanding of fetal and neonatal development. By focusing our attention on variations in genetic code and gene expression between the pre- and postnatal life, pharmacogenomics will likely contribute greatly to our understanding of cellular, tissue, and organ differentiation, physiologic and pathologic fetal development, and important variation in fetal and neonatal drug metabolism.

Fetal exposure to maternal medications may occur as a result of deliberate maternal drug therapy or inadvertent drug exposure. Since the discovery linking thalidomide with birth defects, obstetricians and their expectant patients have had to weigh the balance between maternal drug therapy and potential fetal exposure. As we gain insight into specific medications and their adverse fetal effects, it is clear that not all fetuses exposed to a given medication are at risk for developing its associated malformation. Moreover, if we can identify which fetuses may be at risk during the course of pregnancy, it would greatly benefit expectant mothers taking medications, especially in cases where exposure cannot be avoided as with antiepileptic and antithrombotic medications (1).