Understanding the Risks (and Rewards) of Pills and Pregnancy

Any pregnant woman who has ever cracked open a medicine cabinet is familiar with the warnings against using nearly every kind of medication, including those sold over the counter, from the moment of conception onward. Yet each year in the U.S., some 500,000 pregnant women battle psychiatric illness, cancer, autoimmune disease, influenza and other conditions that require treatment. Leaving aside for a moment the issue of whether the benefits of certain drugs outweigh the risks to the baby, what is the appropriate dosage for a mom-to-be?