Medication use during pregnancy is common with 9 in 10 women taking medication during pregnancy.1 In some cases, certain chronic medications should be continued throughout pregnancy to maintain disease control. Bodily changes and adaptions that occur throughout pregnancy can affect pharmacodynamics, pharmacokinetics, efficacy and potential side effects of these medications. Thus, it is important for providers to understand pharmacology concepts during pregnancy so medication dose adjustments can be made and monitoring performed when appropriate.

While there is some data regarding pharmacology in pregnancy, there is a paucity of information limiting the ability to apply this to all medications and situations. Of the available data, most is observational with a small number of participants. However, there are some principles, evidence, and research to help guide the management of medications during pregnancy. In addition, some medications have well documented recommendations (e.g., levothyroxine, antiseizure medications) for adjustments in pregnancy while others may not. The goal of this review is to help illustrate the potential changes in pregnancy that may help guide discussion with patients about their medications.