Neonatal outcomes of very low birthweight infants born to mothers with hyperglycaemia in pregnancy: a retrospective cohort study in Japan

OBJECTIVE: To examine the mortality and morbidities of very low birthweight (VLBW, <1500 g) infants of mothers with hyperglycaemia in pregnancy. DESIGN AND SETTING: We conducted a retrospective cohort study using data from the Neonatal Research Network of Japan, a nationwide registry of VLBW infants (2003–2012). PATIENTS: We studied 29 626 infants born at 23 to 32 weeks without major congenital anomalies, of which 682 (2.3%) infants were from pregnancies affected by maternal hyperglycaemia. MAIN OUTCOME MEASURES: The primary outcome was hospital mortality. Secondary outcomes were neonatal morbidities and their anthropometric values. Associations between maternal hyperglycaemia and each outcome were observed for the overall period, and statistical tests for interaction were conducted to assess whether they differed before or after the adoption of the International Association of Diabetes in Pregnancy Study Group (IADPSG) guidelines in 2010 for the diagnosis of gestational diabetes mellitus. RESULTS: Overall, hospital mortality (4.1% vs 5.2%), composite outcomes of mortality and severe morbidity (54.2% vs 60%), and anthropometric values were not significantly different between infants of mothers with or without hyperglycaemia in pregnancy. However, the incidence of respiratory distress syndrome (RDS) in VLBW infants from mothers with hyperglycaemia was significantly higher than those from mothers without it only before (relative risk (RR) 1.09, 95% CI 1.00 to 1.19) and not after (RR 0.97, 95% CI 0.83 to 1.11) the adoption of the IADPSG guidelines. CONCLUSION: VLBW infants born to mothers with hyperglycaemia in pregnancy do not seem to be at higher risk of mortality and morbidities, except for RDS only before the adoption of the IADPSG guidelines.