Early pregnancy high normal HbA1c: a high risk group?

Aim: To determine if high normal early pregnancy HbA1c (35-40mmol/mol), in the absence of diabetes, was associated with increased risk of adverse perinatal outcomes compared to normal HbA1c (<35mmol/mol).

Method: A retrospective chart review was carried out on all singleton births in the Wellington region from 1 July 2019 to 31 December 2019. Exclusion criteria were participants domiciled outside the Wellington region, HbA1c ≥50mmol/mol, pre-existing diabetes, gestational diabetes in current pregnancy, no HbA1c performed <20 weeks or the first HbA1c was taken at ≥20 weeks. Baseline characteristics, HbA1c and pregnancy outcomes were obtained. The primary outcome was birth weight and was analysed using multiple linear regression.

Results: There were 1,067 participants in the normal HbA1c (nHbA1c) group and 186 in the high normal HbA1c (hnHbA1c) group. There was no difference in birth weight between hnHbA1c and nHbA1c. hnHbA1c had significantly lower odds of post-partum haemorrhage and composite maternal adverse outcomes compared to nHbA1c (OR 0.52, 95% CI 0.35-0.76) and (OR 0.64, 95% CI 0.46-0.89).

Conclusion: High normal HbA1c was not associated with increased risk of adverse perinatal outcomes in pregnant people who did not develop gestational diabetes.