IDM

Maternal hyperglycemia > fetal hyperglycemia > fetal hyperinsulinemia > increased glycogen synthesis, lipogenesis, protein synthesis (anabolic) > myocardial hypertrophy, extramedullary hematopoeisis

Control of GDM in Mom is crucial

• 3X increased risk of malformations
• Neonatal mortality rate is 5X greater
• Severity of fetal malformations correlates with control of maternal illness
   

Clinical manifestations

• Macrosomic/LGA
• Impaired fetal growth (sec to maternal vasc dz)
• Jumpy, tremulous, hyperexcitable
• Early hypoglycemia in 75% of IDM’s
• Tachypnea/Respiratory distress syndrome
• Cardiac abnormalities: VSD, TGA, Dextrocardia, Hypertophic cardiomyopathy
• CNS malformations: Holoprosencephaly, caudal regression, spina bifida, anencephaly
• Renal dysplasia
• Skeletal malformations
• Hyperbilirubinemia
• Vascular thrombosis (sec to polycythemia)
• Birth injury (sec to macrosomia): Brachial plexus injuries, claviclefxs, visceral injury
• Hypocalcemia
• Small left colon syndrome

Management

• Frequent prenatal evaluations
• Intensive monitoring for hypoglycemia early on
• Evaluate for risk ofpolycythemia, hypocalcemia
• Supportive care for hyaline membrane disease, cardiomyopathy, or other electrolyte abnorm (i.e. hypocalcemia)
• Monitor serial serum glucose: 1 hour after birth, then hourly for 6 hours
• Begin oral/gavagefeedings with glucose water or formula, every 3 hours

Maternal diabetes mellitus can have profound effects on the development and health of the fetus. The severity of the maternal disease and the subsequent fetal effects can vary considerably. Because the maternal diabetic state can be present from the time of conception, early prenatal effects can result in malformations, growth deficiency, and stillbirth. There is a threefold increase in malformations among offspring of diabetic mothers; the incidence is correlated with the severity and level of control of the maternal illness. The most common defects involve the heart, central nervous system, kidneys, and skeleton, as described for the infant in the vignette. Of the cardiac defects, ventricular septal defect, transposition of the great vessels, and dextrocardia are most common. Central nervous system defects can range from anencephaly or holoprosencephaly to spina bifida and hydrocephalus. Malformations of the lower spine also occur and are termed the caudal regression syndrome. The spine may be segmented defectively or terminate in the sacral or lumbar region, resulting in abnormal neurologic function below the level of the defect. Rib defects also may be seen. Although many types of malformations can occur in infants of diabetic mothers, holoprosencephaly and the caudal regression syndrome are characteristic.

Infants of diabetic mothers also may present in the newborn period with macrosomia due to hyperinsulinemia and excessive glucose availability. The macrosomia affects both linear growth and weight. Alternatively, if the diabetic mother has substantial vascular disease, fetal growth can be impaired, resulting in growth retardation. Other complications in infants of diabetic mothers can include hyperbilirubinemia, hypoglycemia, vascular thromboses, respiratory distress, and birth injury due to macrosomia. (see also extended discussion of hypoglycemia in IDM)

Fetal alcohol syndrome is characterized by prenatal growth deficiency, microcephaly, and cardiac defects. Neural tube and vertebral column defects are not common features. Maternal hypothyroidism has little effect on the fetus, which produces its own thyroid hormone; women who have untreated hypothyroidism have been reported to give birth to normal offspring. Maternal iodine deficiency can cause fetal deficiency of the mineral, which results in goiter, signs of cretinism, retarded bone growth, constipation, umbilical hernia, and mottling in the newborn. Prompt treatment with iodine is necessary to prevent mental retardation. Maternal syphilis can affect the fetal skin, mucous membranes, liver, central nervous system, and bones. Cardiac anomalies and open neural tube defects are not common features.

CHLA Board Review 2005 and Prep 2003