Effect of treatment for early gestational diabetes mellitus on neonatal respiratory distress: A secondary analysis of the TOBOGM study.

Objective: To identify factors associated with neonatal respiratory distress (NRD) in early Gestational diabetes mellitus (eGDM).

Design: Nested case-control analysis of the TOBOGM trial.

Setting: Seventeen hospitals: Australia, Sweden, Austria and India.

Population: Pregnant women, <20 weeks' gestation, singleton, GDM risk factors.

Methods: Women with GDM risk factors completed an oral glucose tolerance test (OGTT) before 20 weeks: those with eGDM (WHO-2013 criteria) were randomised to immediate or deferred GDM treatment. Logistic regression compared pregnancies with/without NRD, and in pregnancies with NRD, those with/without high-dependency nursery admission for ≤24 h with those admitted for >24 h. Comparisons were adjusted for age, pre-pregnancy body mass index, ethnicity, smoking, primigravity, education and site. Adjusted odds ratios (95% CI) are reported.

Main outcome measures: NRD definition: ≥4 h of respiratory support (supplemental oxygen or supported ventilation) postpartum. Respiratory distress syndrome (RDS): Supported ventilation and ≥24 h nursery stay.

Results: Ninety-nine (12.5%) of 793 infants had NRD; incidence halved (0.50, 0.31-0.79) if GDM treatment was started early. NRD was associated with Caesarean section (2.31, 1.42-3.76), large for gestational age (LGA) (1.83, 1.09-3.08) and shorter gestation (0.95, 0.93-0.97 per day longer). Among NRD infants, >24 h nursery-stay was associated with higher OGTT 1-h glucose (1.38, 1.08-1.76 per mmol/L). Fifteen (2.0%) infants had RDS.

Conclusions: Identifying and treating eGDM reduces NRD risk. NRD is more likely with Caesarean section, LGA and shorter gestation. Further studies are needed to understand the mechanisms behind this eGDM complication and any long-term effects.