We've all seen these babies with their chubby cheeks and thighs, plethoric color, and poor feeding skills. My first thoughts are always about hyperinsulinemia and hypoglycemia. However, there is so much more to an "infant of a diabetic mother" (IDM) than those immediate symptoms. These babies have complications that may affect them throughout the life span.
The chance of having an IDM in your care is increasing, as the incidence of type 2 diabetes is increasing nationally and internationally. Medically, gestational diabetes is the most common complication of pregnancy. Thirty-five percent of neonates whose mothers have type 1 or type 2 diabetes, and 20% of neonates whose mothers have gestational diabetes, are affected.1 The complications seen in this population run the gamut because just about every major body system, metabolic, pulmonary, cardiovascular, neurological, renal, gastrointestinal, and genetic, and overall growth are affected.
Awareness of the metabolic problems is very high. Healthcare providers are typically on top of the problems with hypoglycemia, with protocols in place for immediate treatment. Hypocalcemia is frequently seen because of a temporary hypoparathyroidism related to maternal and fetal hypomagnesemia. Symptoms include irritability, agitation, and even decreased myocardial contractility.
Another metabolic problem is an increased risk of hyperbilirubinemia, which affects 20% to 30% of IDMs.1 Polycythemia and bruising from birth injury increase the rate of red blood cell breakdown. If born preterm, there will be decreased bilirubin conjugation/excretion and slower transit time through the intestine, producing an additive effective for jaundice.
Polycythemia is common because of the increased metabolic workload of this fetus. Hyperinsulinemia and hyperglycemia increase fetal oxygen consumption and may lead to fetal hypoxia, which stimulates production of erythropoietin. The diabetic mother may have an increased affinity for oxygen, thus providing less to the placenta. The placenta may also be thickened and consume more oxygen, decreasing the amount available to the developing fetus with increased metabolic demands.2 Producing more red blood cells to compensate for the hypoxic environment may mean that other cell lines, such as platelets, are reduced. Transient thrombocytopenia is a common complication. Hyperviscosity syndrome may also be present, resulting in deep vessel thrombosis, especially of the renal vein, and persistent pulmonary hypertension.
Pulmonary function may be affected because of respiratory distress syndrome, transient tachypnea of the newborn, and overall immaturity. Hyperinsulinemia negatively impacts maturation of the lung's surfactant system by reducing production and producing a more unstable surfactant. The risk of respiratory distress syndrome is 6 times higher in IDMs than in non-IDMs, and late preterm IDMs frequently have significant respiratory distress syndrome.3
The cardiovascular system can be impacted structurally or mechanically.3 The incidence of cardiac malformations is approximately 30% and include conotruncal anomalies predominately. Asymmetric septal hypertrophy is present in 25% to 75% of IDMs. The hypertrophy and cardiomegaly may precipitate heart failure with low cardiac output. The development of hypertrophic cardiomyopathy is currently not well understood. The majority of the symptoms subside in approximately 2 weeks, whereas resolution of septal hypertrophy may take as long as 4 months.
An IDM often weighs more than 4000 g, with the majority of the excess weight composed of fat. The diabetic mother has the greatest risk of producing a large neonate when she chronically experiences "spikes" in blood glucose levels of greater than 130 mg/dL after meals. Organomegaly is present due to large deposits of glycogen. Large babies are at high risk for birth injury, including brachial plexus injuries, shoulder dystocia, perinatal asphyxia, and fractures. Perinatal asphyxia is also associated with maternal atherosclerotic vascular disease in type 1 diabetic mothers, occurring at a rate of approximately 25% in neonates.3 Neurological immaturity is manifested in the immature sucking patterns, poor feeding abilities and tendency to be hypotonic and lethargic, jittery, and irritable. Central nervous system anomalies are 16 times higher in IDMs.3 Caudal regression syndrome has been linked to IDMs whose mothers experienced unstable type 1 diabetes.
The gastrointestinal system may have a small left colon, the most common cause of obstruction in IDMs. Of affected neonates, 40% to 50% had a mother with diabetes.4 At birth, the baby may present with symptoms similar to Hirschsprung disease.
Unfortunately, upon discharge of a stable IDM, not all problems have been permanently resolved. As children, they tend to become obese due to significant adipose tissue accumulation. Because of the very high association with later development of type 2 diabetes, this is really a considerable public health problem. According to researchers, fetal hyperinsulinemia, hyperglycemia, and hyperlipidemia are predisposing the IDM to develop adult metabolic syndrome.5 Thus, what has occurred in the prenatal and fetal environment has truly laid the foundation for a myriad of conditions that can resurface at anytime.
-M. Terese Verklan, PhD, CCNS, RNC, FAAN
Professor and Neonatal Clinical Nurse Specialist
University of Texas Medical Branch
School of Nursing and Graduate School of Biomedical Sciences
Galveston, Texas
References