A 35-year-old woman at 38 weeks gestation undergoes induction of labor. The patient has type 2 diabetes mellitus, and her blood glucose levels were increasingly difficult to control during her third trimester despite increasing doses of insulin. During induction, the patient develops arrest of labor and undergoes a cesarean delivery. Apgar scores are 8 and 9 at 1 and 5 minutes, respectively. Physical examination shows a newborn large for gestational age with a birth weight of 4.6 kg (10.1 lb). The remainder of the examination is unremarkable, and vital signs are normal. An hour after delivery, the newborn develops hypoglycemia. Which of the following is most likely the cause of this patient's hypoglycemia?

Question

A 35-year-old woman at 38 weeks gestation undergoes induction of labor.  The patient has type 2 diabetes mellitus, and her blood glucose levels were increasingly difficult to control during her third trimester despite increasing doses of insulin.  During induction, the patient develops arrest of labor and undergoes a cesarean delivery.  Apgar scores are 8 and 9 at 1 and 5 minutes, respectively.  Physical examination shows a newborn large for gestational age with a birth weight of 4.6 kg (10.1 lb).  The remainder of the examination is unremarkable, and vital signs are normal.  An hour after delivery, the newborn develops hypoglycemia.  Which of the following is most likely the cause of this patient's hypoglycemia?

Quizplus · Accepted Answer

11ec160b_39ff_0bbd_9249_4d4cc7a13bcf_MD0001_00 Diabetes mellitus in pregnancy is associated with a number of neonatal complications. In pregnant women with poorly controlled diabetes mellitus, the fetus is subjected to high blood glucose levels because glucose freely crosses the placenta. The resulting fetal hyperglycemia leads to a compensatory pancreatic beta cell hyperplasia and subsequent increase in fetal insulin production (eg, hyperinsulinemia). The resultant fetal hyperinsulinemia causes the following neonatal complications: Hypoglycemia: After delivery, the fetus is no longer exposed to high glucose levels; however, due to beta cell hyperplasia, the neonate continues to secrete high levels of insulin, resulting in symptomatic low glucose levels (eg, jitteriness, irritability) Polycythemia: Increased fetal metabolism and increased fetal oxygen demand, resulting in hypoxemia and a compensatory rise in fetal erythropoietin (ie, polycythemia) Macrosomia: Increased central adipose deposition (abdominal and interscapular), leading to increased delivery complications (eg, shoulder dystocia, cesarean delivery) (Choice B) Maternal insulin is not transferred to the fetus but instead is catabolized by the placenta; therefore, even with increasing maternal insulin use, the neonate is not affected because of placental metabolism. (Choice C) Cortisol deficiency in the newborn period is likely due to primary adrenal insufficiency, which would present with hypotension and electrolyte abnormalities in addition to hypoglycemia. (Choice D) Glycogen storage diseases are caused by enzymatic defects that impair glycogenolysis and typically present with hypoglycemia and lactic acidosis. However, they are not evident immediately after birth because the neonates have frequent glucose resupply (from frequent breastfeeding) and, therefore, do not depend on the breakdown of glycogen. (Choice E) Fetal hyperglycemia can result in increased secretion (not impaired production) of insulin-like growth factor 2 (IGF-2), causing macrosomia. (Choice F) Insulin promotes glucose storage in the liver as glycogen; therefore, infants of mothers with poorly controlled diabetes have increased glycogen stores. However, despite hypoglycemia, these infants have poor mobilization of glycogen (glycogenolysis) due to islet hyperplasia and the resultant hyperinsulinemia. Educational objective: Neonates born to mothers with poorly controlled diabetes during pregnancy are exposed to high maternal glucose levels in utero, resulting in beta cell hyperplasia followed by excessive fetal insulin production. Fetal hyperinsulinemia causes neonatal hypoglycemia, polycythemia, and macrosomia.

A 35-Year-Old Woman at 38 Weeks Gestation Undergoes Induction of Labor