Pregnancy leads to diverse physiologic changes to accommodate the demands of the developing fetoplacental unit, which affect many major organ systems. Understanding these physiologic adaptations to pregnancy is important for all clinicians because they have important implications for the diagnosis and management of various disorders. This article provides a brief overview of the most notable of these adaptations, including cardiovascular, hematologic, respiratory, renal, immunologic, and gastrointestinal. Clinical correlate of pharmacokinetics and a patient case study are included.