FDA pregnancy risk categories and the CPS: do they help or are they a hindrance?

My patient is taking a medication for a chronic condition and has just found out that she is 6 weeks pregnant. The US Food and Drug Administration (FDA) has assigned this medication to pregnancy risk category D, and the Compendium of Pharmaceuticals and Specialties provides no additional data. How should I interpret this information, and how does the Motherisk Program evaluate the safety or risks of drug use in pregnancy?

Pregnancy safety data provided by the FDA pregnancy risk categories and the Compendium of Pharmaceuticals and Specialties are insufficient to guide clinical decisions on how to proceed with a pregnancy following exposure to a category D medication. The Motherisk Program creates peer-reviewed statements derived from the primary literature, and we examine fetal outcomes as well as the risk-benefit profile of maternal treatment when evaluating the safety of medication use in pregnancy. The FDA announced in May 2008 that it is dropping its pregnancy risk categories and adopting a method similar to the one we use at Motherisk.