Pregnancy and the fetus

Abstract Pregnant women constitute a uniquely challenging patient population as clinical decisions cannot be made solely on the basis of the woman’s needs but must also consider the impact of any therapeutic intervention on the developing fetus. As the health of the woman and that of her fetus are intertwined, any treatment designed to benefit one will inevitably affect the other. Further complicating matters is the fact that the initiation and maintenance of a healthy, viable pregnancy induces a wide variety of physiological changes that alter plasma hormone concentrations relative to the nonpregnant state. For the clinical laboratorian and care team, it is essential to understand these changes and interpret laboratory values in the context of the appropriate reference interval for the given stage of pregnancy. What is considered “normal” changes throughout pregnancy, particularly the concentrations of steroid and protein hormones measured in the evaluation of endocrine function. This chapter will describe typical endocrine function during pregnancy, highlight endocrine changes consistent with normal and abnormal pregnancy, and suggest strategies to apply clinical laboratory testing to guide patient care.