You've probably heard that it's best to avoid prescription drugs during pregnancy. Actually, this is true of all pharmaceuticals -- prescription and over the counter -- because many pharmaceuticals can cross the placenta and affect your developing baby. The Federal Drug Administration, or FDA, uses a pregnancy ranking system for drugs to help you and your doctor determine whether a particular drug is safe during pregnancy.
Prescription Drugs and Pregnancy
Prescription drugs, like over-the-counter drugs and other chemicals, have the potential to cross the placenta, which is the organ that transfers oxygen and nutrients from you to your baby. In some cases, drugs that are perfectly safe when you're not pregnant can harm your unborn baby. One example is thalidomide, which is an antinausea drug used by chemotherapy patients and those with Hansen's disease, but which causes severe birth defects in unborn babies, and is therefore inappropriate during pregnancy.
Risks and Benefits
Most obstetricians use a risk-to-benefit ratio to help them determine whether you should be taking a particular prescription drug during pregnancy. There is a risk associated with nearly any prescription drug, particularly during pregnancy. If the drug benefits a pregnant woman so significantly, however, that it's worth the risk, the obstetrician will typically prescribe or allow the drug.
FDA Guidelines
The FDA provides a classification system for drugs so that obstetricians and patients can assess the risk involved in using a particular pharmaceutical. A risk category of "A" indicates that there's scientific proof that a drug does no harm, while a rating of "B" indicates that there's no evidence of risk in humans. Category "C" drugs have shown harmful effects in animals, but not in humans, while "D" drugs have shown harmful effects in humans. Category "X" drugs are not to be used during pregnancy, as there is significant scientific evidence of harm.
Considerations
As helpful as the rating system is in theory, in practice, it can be hard to determine whether a prescription drug is actually safe in pregnancy. This is because there are no controlled, scientifically based studies conducted on pregnant women for ethical reasons. As a result, very few drugs fall into categories A and B; most are category C. If you have a condition that isn't life- or livelihood-threatening and that doesn't have to be treated during pregnancy, your obstetrician will likely recommend that you don't use pharmaceuticals to treat the condition. If you have asthma or another serious condition, however, your obstetrician will likely recommend the safest drug possible, since the risk of not treating the condition is greater than the risk of using prescription drugs.
References
- "You: Having A Baby"; Michael Roizen, M.D. and Mehmet Oz, M.D.; 2009
- American Pregnancy Association: FDA Drug Category Ratings
