- May be SGA or LGA, with or without congenital anomalies and with or without birth injury.
- IDM is caused by chronic hyperglycemia in the mother (e.g., gestational diabetes mellitus or long-term diabetes mellitus with or without vascular changes).
- Hyperglycemia in the mother without vascular changes causes large amounts of amino acids, free fatty acids, and glucose to be transferred to the fetus, but maternal insulin does not cross the placenta.
- The fetal response to these transferred substances includes:
- Islet cells of the pancreas enlarge (hypertrophy).
- Hypertrophic cells produce large volumes of insulin, which acts as a growth hormone, and protein synthesis accelerates.
- Fat and glycogen are deposited in fetal tissue, and the fetus grows large (macrosomia), especially if maternal blood glucose levels are not well controlled in the third trimester.
- Various unknown factors also may contribute to changes.
- In maternal long-term diabetes with vascular changes, the newborn may be SGA because of compromised placental blood flow, maternal hypertension, or pregnancy-induced hypertension, which restricts uteroplacental blood flow.
- Associated complications in IDM include:
- Fractures and nerve damage may occur from birth trauma if the infant is LGA.
- Congenital anomalies (e.g., heart, kidney, vertebral, and CNS) are three to five times more common, with incidence decreasing if maternal blood glucose levels remain controlled and normal during the first trimester.
- Risk for respiratory distress syndrome increases (high insulin levels interfere with production of pulmonary surfactant).
- Hypoglycemia may result after birth from lack of glucose from the mother, but continued production of insulin by the newborn.
- Hypocalcemia may result from decreased parathyroid hormone production.
- Polycythemia (ie, hematocrit exceeding 65%) may result from placental insufficiency causing chronic fetal hypoxia and increased fetal erythropoietin production.
- Organ damage may result from decreased blood flow and renal vein thrombosis.
- Hyperbilirubinemia may result from breakdown of excess RBCs after birth.
1. Clinical manifestations
- Congenital anomalies are more likely in IDMs who are SGA than in other SGA newborns.
- Size differences and variations are more common in IDMs who are LGA than in other LGA newborns.
- Greater size results from fat deposits and hypertrophic liver, adrenals, and heart.
- Length and head size are usually within normal range for gestational age.
- Observation reveals the characteristics appearance of a round, red face and an obese body.
- Possible signs and symptoms of hypoglycemia include jitteriness, irritability, diaphoresis, and blood glucose level less than 45 mg/dL.
- Possible signs and symptoms of hypocalcemia include jitteriness, twitching, and a high-pitched cry.
2. Laboratory and diagnostic study findings.
- Blood glucose evaluation at 30 and 60 minutes and at 2,4,6, and 12 hours after birth as directed by nursery protocol
- If results are abnormal, repeat testing every 30 to 60 minutes until newborn achieves stable level; also test before each feeding for 24 hours.
- If reagent strips indicate blood glucose levels less than 45 mg/dL, findings should be verified by laboratory and reported to pediatrician.
- Serum electrolyte studies may reveal hypocalcemia (total serum calcium mg/dL).
- Hematocrit level may be elevated, indicating polycythemia.
1. Establish an initial database.
- Review the mother’s health history and history of the pregnancy.
- Complete an initial newborn examination and assess for birth injuries.
2. Monitor for complications.
- Monitor for signs and symptoms of hypoglycemia (see table 1)
- Measure the newborn’s glucose level according to nursery protocol.
- Feed the newborn early according to nursery protocol to prevent or treat hypoglycemia.
- If signs and symptoms continue after feeding, observe for other complications.
- Monitor for signs of hypocalcemia (see table 2)
- Obtain hematocrit value; report the findings to the physician.
- Observe for signs of respiratory distress (e.g., nasal flaring, grunting, retractions, and tachypnea).
- Initiate gavage feeding if the newborn cannot suck well or if the respiratory rate exceeds normal (30 to 60 breaths per minute).
3. Maintain a neutral thermal environment.
4. Provide education and emotional support.
Table 1 Signs and Symptoms of Hypoglycemia
Table 2 Signs of Hypocalcemia