Maternal blood glucose levels, BMI linked to stillbirth risk
medwireNews: A Scottish study has identified glycated hemoglobin (HbA1c) levels and BMI as modifiable risk factors for stillbirth among pregnant women with diabetes.
Robert Lindsay (University of Glasgow, UK) and colleagues analyzed data from all births involving women with pregestational diabetes in Scotland over an 18-year period (1998–2016), comprising 3778 singleton babies born to 2582 women with type 1 diabetes and 1614 infants born to 1265 mothers with type 2 diabetes. Stillbirth rates among women with type 1 and type 2 diabetes were 16.1 and 22.9 cases per 1000 births, respectively.
For mothers with type 1 diabetes, average pre-pregnancy HbA1c levels were a significant 11 mmol/mol (1%) higher among those with pregnancies ending with stillbirth versus live birth. Both pre- and peri-pregnancy HbA1c levels were significantly associated with stillbirth risk after adjustment for maternal age, diabetes duration, and Scottish Index of Multiple Deprivation.
Moreover, the researchers found that shorter diabetes duration and lower BMI were “weakly,” albeit statistically significantly, associated with stillbirth risk among women with type 1 diabetes.
For patients with type 2 diabetes, average BMI was significantly higher among those with pregnancies resulting in stillbirth compared with live birth, at 38.2 versus 33.9 kg/m2. Higher BMI and higher pre-pregnancy HbA1c were both significantly associated with stillbirth risk after adjustment for confounding factors, but HbA1c levels during pregnancy were not.
These findings suggest that “[m]aternal blood glucose levels and BMI are important modifiable risk factors for stillbirth in diabetes,” write Lindsay and colleagues in Diabetologia.
“Methods of supporting women to improve blood glucose levels in pregnancy along with programmes to optimise weight before pregnancy may help reduce stillbirth rates but are often challenging to implement successfully,” they add.
Despite stillborn babies being delivered significantly earlier on average than livebirth infants for both mothers with type 1 (33.8 vs 36.6 weeks) and type 2 diabetes (33.7 vs 37.2 weeks), Lindsay and team note that a third of stillbirths occurred at term, with the highest rates at week 38 for mothers with type 1 diabetes and at week 39 for those with type 2 diabetes.
In light of these findings, the investigators suggest that “earlier delivery may be considered an attractive option” to reduce stillbirth risk. However, they caution that the possible benefits must be “balanced against increased risk of complications such as neonatal respiratory distress syndrome.”
They say that such risks “would need to be more formally explored before recommendations for optimal timing of delivery are made, especially considering the very low representation of mothers with diabetes in current studies.”
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