Safe Threshold of Capillary Blood Glucose for Predicting Early Future Neonatal Hypoglycaemia in Babies Born to Mothers With Gestational Diabetes Mellitus, an Observational Study

Abstract Background: There is increasing pressure to get women and babies home rapidly after birth. Babies born to mothers with gestational diabetes mellitus (GDM) currently get 24-hour inpatient monitoring. We investigated whether a low-risk group of babies born to mothers with GDM could be defined for shorter inpatient hypoglycaemia monitoring. Methods: Observational study conducted in a tertiary maternity hospital in 2018. Singleton, term infants born to women with GDM and no other risk factors for hypoglycaemia, were included. Capillary blood glucose (BG) testing and clinical observations for signs of hypoglycaemia during the first 24-hours after birth. BG was checked in all babies before the second feed. Subsequent testing occurred if the first result was <2.0mmol/L, or clinical suspicion developed for hypoglycaemia. Neonatal hypoglycaemia, defined as either capillary or venous glucose ≤2.0mmol/L and/or clinical signs of neonatal hypoglycaemia requiring oral or intravenous dextrose (lethargy, abnormal feeding behaviour or seizures). Results: Fifteen of 106 babies developed hypoglycaemia within the first 24-hours. Maternal and newborn characteristics were not predictive. All babies with hypoglycaemia had an initial capillary BG ≤2.6mmol/L (Area under the ROC curve (AUC) 0.96, 95% Confidence Interval (CI) 0.91-1.0). This result was validated on a further 65 babies, of whom 10 developed hypoglycaemia, in the first 24-hours of life.Conclusions for practice: Using the 2.6mmol/L threshold, extended monitoring as an inpatient could have been avoided for 60% of newborns in this study. Whilst prospective validation is needed, this approach could help tailor postnatal care plans for babies born to mothers with GDM.