Evaluating medication use in pregnancy and lactation: what every pharmacist should know.

As a pharmacist, being asked to give advice about medication use during pregnancy or lactation can be daunting. This article reviews the principles of drug transfer across the placenta, into breast milk, and reviews the rating scales and different resources available. The Food and Drug Administration classification scale is reviewed and the upcoming changes are explained, along with recent labeling changes for specific medications or drug classes when appropriate. This article provides the pharmacist with a practical set of tools to review the information available and assess the risks of treating or withholding a medication for mother and infant.