We have shown previously that recent changes to the diagnostic guidelines for Gestational Diabetes Mellitus (GDM) increase the occurrence of GDM. The aim of this study was to compare in the same retrospective data maternal and neonatal complications between groups diagnosed using the new and old criteria in order to assess the impact on pregnancy outcomes.
The study population was 647 women, most of who were diagnosed under previous guidelines following 50g glucose screening. Oral glucose tolerance testing (OGTT) and pregnancy care was at a tertiary centre between 2011 and 2015. All neonates were singletons.
Neonates born to women now excluded from a GDM diagnosis with 120 min glucose concentration (8.1-8.4 mmol/L) had significantly less NICU/SCN admissions (5.8% s 13%; Χ2, p=0.031) and 60% less premature deliveries (i.e. ≤37 wks gestation) (Χ2, p=0.021) . Women diagnosed by new fasting criterion (5.1-5.4 mmol/L) and the new 60 min group (≥10 mmol/L) both had significantly more macrosomic neonates (i.e. birth weight ≥90%ile) in comparison to all other groups (18-20% vs <5%, Χ2, p ≤ 0.005) and statistically fewer small for dates babies (7.9% vs 19.1% in new 120 min group) (Χ2, p = 0.006).
Overall low APGAR scores (<7 at 1 and 5 min) were reflected in the number of admissions to NICU/SCN and was greatest in the new fasting group (18% and 6% respectively).
The number of LUSCS was statistically lowest (29.8%) in the new 120 min group and highest in the fasting group (42.1%) (Χ2, p=0.017).
Outcomes support the lowering of the fasting diagnostic criterion to extend management of GDM to limit growth of large birth weight neonates and their sequelae. The 120 min groups had an increased occurrence of low weight neonates, which might decrease with a review of management in this group.