Stillbirth risk in type 1 and type 2 diabetes quantified

By Bianca Nogrady
One-third of stillbirths in mothers with type 1 or type 2 diabetes are occurring at term, with maternal blood glucose and BMI the most important modifiable risk factors, Scottish research suggests.

A retrospective cohort study published in Diabetologia looked at delivery outcomes from 3778 singleton deliveries to mothers with type 1 diabetes and 1614 to mothers with type 2 diabetes between 1998 and 2016.

It found that in women with type 1 diabetes, higher HbA1c before pregnancy was associated with a significant 3% increase in the risk of stillbirth, whereas higher HbA1c later in pregnancy was associated with a significant 6% increase in the risk of stillbirth.

Among mothers with type 2 diabetes, higher maternal BMI was associated with a 7% higher risk of stillbirth, and a higher prepregnancy HbA1c was associated with a 2% higher risk of stillbirth.

Overall, the stillbirth rates were 16.1 per 1000 women with type 1 diabetes, with the highest incidence seen in the 38th week of pregnancy, and 22.9 per 1000 in women with type 2 diabetes, with the highest rate occurring in the 39th week.

The study authors noted that maternal blood glucose and BMI were the main modifiable risk factors associated with stillbirth in women with diabetes, but it was difficult to predict exactly which pregnancies would end in stillbirth.

Commenting on the study, Dr Adrienne Gordon, neonatal staff specialist at Royal Prince Alfred hospital and a researcher at The University of Sydney, said it was useful in separating out the increased risk between women with type 1 and type 2 diabetes, and showing that type 2 diabetes presented a higher risk of stillbirth.

Dr Gordon, also chief investigator with the Stillbirth Centre of Research Excellence, noted that the higher incidence of late-term stillbirth suggested some could be avoided with a planned earlier delivery, a practice that occurred more often in recent years in Australia than in the earlier years in the Scottish data.

‘That does need careful consideration, however, because if you deliver early, you might avoid late stillbirth but there are morbidities, such as respiratory problems for the baby, that must be considered,’ she told Medicine Today.
Diabetologia 2019;