Pregnancy Complicated by Diabetes Mellitus

Diabetes mellitus that results from relative or absolute lack of insulin is encountered during pregnancy in two situations: pregestational diabetes mellitus (pre-GDM) and gestational diabetes mellitus (GDM). The former refers to women who had diabetes mellitus prior to conception, with microvascular diabetes-associated complications (renal, retinal, cardiac, and nervous system), and the latter refers to otherwise healthy women who developed glucose intolerance during the index pregnancy. These two entities are entirely distinct from both obstetric and neonatal perspectives. Pre-GDM and its associated small vessel injury may affect placental function and fetal growth, whereas GDM is a transient problem that affects the fetus in the opposite way (i.e., macrosomia and its obstetrical consequences—dystocia and increased incidence of operative delivery). This chapter focuses mainly on GDM and its neonatal consequences.