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The Neonatal Risks Associated with Gestational Diabetes Mellitus

Jun 11, 2019
 
Editor: Steve Freed, R.PH., CDE

Author: Adam Chalela, B.S. Doctor of Pharmacy Candidate USF College of Pharmacy

Which baseline characteristics in pregnant mothers predispose higher neonatal risks of adverse events?

During pregnancy, expecting mothers possess an innate risk for the development of gestational diabetes. Data is currently conflicted on which exact risks are posed to the unborn fetus or newborn infant in mothers who develop gestational diabetes during pregnancy. It is current practice for expecting mothers to be specifically screened for the presence of gestational diabetes at week 24 of pregnancy and onward, but new evidence shows that the disease may be present earlier. Earlier diagnoses of gestational diabetes have also shown association towards increased neonatal risks, especially hypoglycemia and hyperbilirubinemia.

This developing evidence has led researchers out of the Western Sydney University of Medicine in Australia to conduct a retrospective chart review of mothers who had been diagnosed with gestational diabetes to see exactly which maternal risk factors show significant association towards episodes of hypoglycemia and hyperbilirubinemia in newborn infants. A total of 749 women were enrolled from a single center in Sydney, Australia and numerous baseline characteristics from both the mother and neonate were collected.

Incidence of neonatal hypoglycemia was met if the neonate’s blood glucose values dropped lower than 32.4 mg/dL at any time within the first 24 hours after birth, as defined by a previous guideline. Incidence of neonatal hyperbilirubinemia was met if total serum bilirubin was below threshold enough to precipitate jaundice within the first 150 hours after birth, as defined by institutional protocol.

Results from a total of 767 live births were analyzed; mothers who birthed twins or triplets were observed as independent situations and not included in the primary analysis of single births. The average mother was white, in their early thirties, had a normal pre-pregnancy BMI, and underwent vaginal delivery of their baby, though a wide variety of patient populations were studied. Pregnancies that lacked postnatal chart records, resulted in newborn jaundice from other known causes, and stillbirth were excluded from primary analysis.

A total of 7.8% of infants that were born developed hypoglycemia within the first day of being born, 7.5% developed hyperbilirubinemia, and only 1.7% developed both. Results from the study found that neonatal development of hypoglycemia was an independent factor associated with a younger gestational age at diagnosis of gestational diabetes. However, association between gestational diabetes and development of hyperbilirubinemia was not observed within the selected patient population. Other factors that increase risk of neonatal hypoglycemia, but not hyperbilirubinemia, include a higher degree of maternal hyperglycemia during an oral glucose tolerance test and a past medical history of macrosomia. Expecting mothers who were pregnant with more than a singular child had a 10.8% increased risk of neonatal hypoglycemia and a 26.4% higher risk of hyperbilirubinemia compared to those who had single pregnancies; other risk factors for the development of these conditions were significantly lower.

The conclusion of this study leads to the consideration of earlier screening of gestational diabetes in expecting mothers. The risks of early development of gestational diabetes could result in negative outcomes for the newborn infant such as hypoglycemia which can precipitate further complications such as earlier gestation, lower appearance, pulse, grimace, activity, and respiration (APGAR) scores, and hyperbilirubinemia. Further studies are warranted to determine the effectiveness of earlier screening in high-risk populations and intensive glycemic control in patients at risk for the development of gestational diabetes.

Practice Pearls

  • Early incidence of gestational diabetes is associated with higher neonatal risks of hypoglycemia and hyperbilirubinemia.
  • Neonatal hypoglycemia predisposes newborn infants to lower APGAR scores and higher birth weights.
  • Providers should consider early screening of gestational diabetes in expecting mothers, especially in instances of multiple pregnancies.

Reference: Thevarajah A, Simmons D. Risk factors and outcomes for neonatal hypoglycemia and neonatal hyperbilirubinemia in pregnancies complicated by gestational diabetes mellitus: a single center retrospective 3-year review. Diabet Med 2019;[Epub ahead of print]. DOI: 10.1111/dme.13962.

Adam Chalela, B.S. Doctor of Pharmacy Candidate USF College of Pharmacy