Early pregnancy high normal HbA1c: A group of higher risk women?  — ASN Events
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Early pregnancy high normal HbA1c: A group of higher risk women?  (#53)

Megan J Chatfield 1 , Lisa Woods 2 , Ella Sussock 3 , Rosalie E Elder 1 , Rosemary M Hall 4 5
  1. Department of Obstetrics and Gynaecology, Wellington Regional Hospital, Te Whatu Ora CC and HV, Wellington
  2. School of Mathematics and Statistics, Victoria University of Wellington, Wellington
  3. Department of Obstetrics and Gynaecology, University of Otago, Wellington
  4. Department of Endocrinology, Wellington Regional Hospital, Te Whatu Ora CC and HV, Wellington
  5. Department of Medicine, University of Otago, Wellington

Background

Hyperglycaemia in pregnancy below the threshold for diabetes is associated with an increased risk of adverse perinatal outcomes.1 HbA1c early in pregnancy may identify those at most risk but the physiologic decrease in early pregnancy HbA1c may be falsely reassuring. Therefore, it is possible that women with “high normal” early pregnancy HbA1c may have higher risk of adverse perinatal outcomes.

Aim

The aim of this study was to determine if, in women without pre-existing diabetes or gestational diabetes, early pregnancy HbA1c within the upper limit of normal (35-40 mmol/mol) was associated with increased risk of adverse perinatal outcomes compared to normal HbA1c (<35 mmol/mol).

Methods

A retrospective chart review was carried out on all singleton births at Wellington Regional Hospital, Kenepuru Maternity Unit and Paraparaumu Maternity Unit between 1 July 2019 to 31 December 2019. Exclusion criteria were women domiciled outside the Wellington region, HbA1c ≥ 50 mmol/mol, pre-existing diabetes mellitus, gestational diabetes, no HbA1c performed <20 weeks gestation or the first HbA1c was taken at ≥20 weeks gestation. Baseline characteristics, HbA1c, and pregnancy outcomes were obtained. The primary outcome was birth weight and was analysed using multiple linear regression.

Results

There were 1067 women in the normal HbA1c (nHbA1c) group and 186 women in the high normal HbA1c (hnHbA1c) group. Women in the hnHbA1c group had a higher BMI (25.4 kg/m2 vs. 24.4 kg/m2, p = 0.0263) and were more likely to be of Pacific, Indian or Other Asian ethnicity compared to women in the nHbA1c group (p < 0.05). Women with hnHbA1c had significantly lower odds of experiencing a post-partum haemorrhage compared to women with nHbA1c (OR 0.524, 95% CI 0.353-0.762). When adverse outcomes were grouped in composite, women with hnHbA1c had significantly lower odds of adverse outcomes (OR 0.640, 95% CI 0.462-0.888), with or without controlling for parity. Increasing BMI was associated with an increased likelihood of having a macrosomic baby (OR 1.060, 95% CI 1.036-1.085), caesarean section versus normal vaginal delivery (OR 1.024, 1.005-1.044), post-partum haemorrhage (OR 1.028, 1.009-1.048) and induction of labour (OR 1.042, 1.020-1.063), as well as composite neonatal adverse outcomes (OR 1.024, 1.006-1.043).

Conclusions

In this study high normal HbA1c was not associated with increased risk of adverse perinatal outcomes. Our findings add to the evidence that increased BMI is a risk factor for adverse outcomes in pregnancy, and strategies to address this must be prioritised.

 

  1. Metzger BE, Lowe LP, Dyer AR, et al. Hyperglycemia and adverse pregnancy outcomes. N Engl J Med 2008; 358:1991–2002.
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