Screening at 24 weeks of gestation reveals that a pregnant woman has gestational diabetes mellitus (GDM). In planning her care, the nurse and the woman mutually agree that an expected outcome is to prevent injury to the fetus as a result of GDM. The nurse identifies that the fetus is at greatest risk for

A. Macrosomia, defined as a birth weight greater than 4,000–4,500 grams, is the most common fetal complication associated with gestational diabetes. Hyperglycemia in the mother leads to increased glucose transfer across the placenta, stimulating fetal pancreatic insulin production. Fetal hyperinsulinemia acts as a growth-promoting hormone, resulting in excessive fat and muscle deposition and ultimately large-for-gestational-age infants. Macrosomia increases the risk of birth injuries such as shoulder dystocia, clavicle fractures, and the need for cesarean delivery. B. Preterm birth is not the primary risk associated with GDM. While poorly controlled diabetes can contribute to preterm labor, it is less common than macrosomia. The main concern in GDM is excessive fetal growth, not premature delivery. C. Low birth weight is not typically associated with gestational diabetes. In fact, infants of mothers with poorly controlled GDM are often larger than average, not smaller, due to fetal hyperinsulinemia and increased nutrient availability. D. Congenital anomalies, particularly neural tube defects or central nervous system defects, are primarily associated with pregestational diabetes rather than GDM. Gestational diabetes develops later in pregnancy (usually after 24 weeks) when organogenesis has largely occurred, so the risk for major congenital anomalies is minimal.