Women's health: pregnancy and childbirth. The use of drugs during pregnancy and lactation.

It is a regulatory fact that only 14 drugs are approved for use during pregnancy; none of them is specifically approved for use in nursing mothers. With the current emphasis on breast feeding, more data describing levels of drugs in fetal blood and drug levels in breast milk are necessary. Some of the pharmacologic properties useful in predicting drug transmission during lactation include lipid solubility, ionization constant, and molecular size (which predisposes a drug to crossing membrane barriers to the fetus and the milk).