**Core Concept:** Diabetes in pregnancy, specifically gestational diabetes, can lead to macrosomia (large body size) and increased risk of complications in the newborn. The fetal overgrowth is due to high glucose levels in the mother, which crosses the placenta and contributes to fetal growth.

**Why the Correct Answer is Right:** In this case, the most likely abnormality in the child is macrosomia (Option D). Macrosomia occurs when a baby grows abnormally large due to increased fetal growth factors, such as high maternal glucose levels from gestational diabetes. These high glucose levels cross the placenta and stimulate fetal growth. Macrosomic infants are at risk for complications during labor and delivery, such as shoulder dystocia, brachial plexus injury, and birth trauma.

**Why Each Wrong Option is Incorrect:**

A. Hypoglycemia (low blood sugar) is not a common issue in infants born to diabetic mothers. In this scenario, the glucose levels are high, not low, and lead to macrosomia, not hypoglycemia.

B. Hypocalcemia (low blood calcium) is rarely associated with diabetes in pregnancy. The focus here is on excessive fetal growth, not blood calcium levels.

C. Congenital abnormalities are not specifically increased in infants born to diabetic mothers with macrosomic infants. While diabetes in pregnancy increases the overall risk of congenital anomalies, macrosomic infants are more likely to experience complications during labor and delivery, not congenital abnormalities.

**Clinical Pearl:** In cases of gestational diabetes, close monitoring and appropriate management of maternal blood glucose levels are essential to prevent complications in the newborn. Adequate prenatal care and management of diabetes can significantly reduce the risk of macrosomia and its associated complications.