Until present, women with diabetes have a significantly higher risk of stillbirth during pregnancy. Poorly controlled diabetes with high long-term blood sugar, overweight, or obesity are the most important risk factors that can potentially have an influence on this, as a data evaluation from two Scottish registries has shown.
According to previous data, the risk of stillbirth is four to five times higher for pre-existing diabetes than for pregnant women without diabetes. While the incidence of stillbirths has decreased significantly in other populations in recent decades, it has remained almost the same in diabetic patients over this period.
The research group led by Sharon T. Mackin at the University of Glasgow, UK, has set itself the goal of generating new data on the incidence of stillbirths in women with pre-existing diabetes, as well as finding predictors and possibly influenceable risk factors. For this purpose, they evaluated the data of the "Scottish Morbidity Record 02" (SMR02), in which all stillbirths occurring in Scotland are recorded, and related them to the diabetes register "Scottish Care Information-Diabetes" (SCI-Diabetes). A total of 5,392 single children of diabetic mothers were identified, including 3,778 babies of mothers with type 1 diabetes and 1,614 children of mothers with type 2 diabetes. Stillbirth was defined as when the birth took place in or after the 24th week of gestation and the children did not breathe or show signs of life after birth.
Among women with type 1 diabetes, 16.1 stillbirths occurred per 1,000 births; among women with type 2 diabetes, 22.9 stillbirths occurred per 1,000 births. Although type 2 diabetes had existed on average for only 4.4 years (compared to 11.2 years for type 1 diabetes), the risk of stillbirth was higher. In the observation period between 1998 and 2016, the rate of stillbirths in mothers with type 1 diabetes hardly changed, while it decreased slightly in mothers with type 2 diabetes.
The most important and potentially avoidable risk factor in both forms of diabetes was long-term blood sugar. In women with type 1 diabetes who had a stillbirth, the average blood sugar level (HbA1c) at all stages of pregnancy was significantly higher than in diabetics with live births. Type 2 diabetes, on the other hand, was different: here an increased HbA1c value in the period before pregnancy was associated with an increased rate of stillbirths. In women with type 2 diabetes who wish to have children, blood glucose control should, therefore, be optimized as far as possible before pregnancy, the authors write.
Another important risk factor was high body weight in women with type 2 diabetes. Even in women who had a live child, the BMI was clearly too high at 33.9 kg/m2 - in women with stillbirth, the BMI was even higher at 38.2 kg/m2. The high BMI proved to be an independent risk factor here, also taking into account other potential risk factors such as mother's age, diabetes duration, smoking, tobacco consumption or social deprivation. Interestingly, 81% of stillbirths in women with type 2 diabetes were boys, compared to 54.1% in women with type 1 diabetes.
One-third of stillbirths occurred in this study on the calculated date. In type 1 diabetes, most stillbirths occurred in the 38th week and in type 2 diabetes in the 39th week of gestation. The unanswered question in this study is whether the rate of stillbirths can be reduced by early delivery - usually by cesarean section. Although the authors were able to calculate that 22 stillbirths could possibly have been prevented in women with type 1 diabetes by routine induction of birth in the 37th week of gestation, 12 in women with type 2 diabetes, the risks of a caesarean section birth and an increased rate of respiratory problems in children should be weighed against this. According to the authors, it may be somewhat easier for male children of women with type 2 diabetes to decide to induce early birth.
Conclusion: Optimised blood glucose control and a reduction diet for obesity may lower the risk of stillbirth in pregnant women with pre-existing diabetes.
Source:
Sharon T. Mackin et al; Factors associated with stillbirth in women with diabetes, Diabetologia (2019); 62(10): 1938-47; DOI: https://doi.org/10.1007/s00125-019-4943-9
https://link.springer.com/article/10.1007%2Fs00125-019-4943-9