Abstract
When a woman learns that she is pregnant, her emotions are like a roller coaster. To her, she is pregnant. She begins to plan all the things that could be and is in constant motion to await the 9 months until the arrival of her bundle of joy. However, to those of us in the perinatal nursing field, it means so much more. The pregnant woman's body goes through some profound anatomical, physiologic, and biochemical changes to adapt to and support the entire pregnancy, which ultimately support the growing fetus. Although these physiologic changes are normal, often they can be misinterpreted as disease. These changes may also unmask or worsen a preexisting condition or disease, ultimately because the pregnant woman's body cannot adequately adapt to the changes of pregnancy. It is essential to know and understand the physiology-the inner workings-of both the mother and the fetus. This includes the basic adaptations related to pregnancy, placental physiology and action, uterine activity physiology, and fetal heart rate regulation, although this article will focus on maternal and uterine physiology only.