Obese, Diabetic Pregnant Women More Likely to Suffer Stillbirths

Highlights:

• Higher maternal BMI (body mass index) and blood sugar levels found to be critical determinants in increasing risk of stillbirths in women with diabetes
• Almost a third of stillbirths occur close to term introducing policy changes and planning earlier delivery may be beneficial. In the rest of the cases, improving methods to detect babies at risk is crucial to reduce the occurrence of stillbirths
• Additionally, risk of stillbirth in diabetic women is higher with babies who are either small for gestational age or large for gestational age

In pregnant women with diabetes, maternal BMI (body mass index) and blood sugar levels found to be critical determinants in increasing risk of stillbirths, according to a recent study at the Institute of Cardiovascular and Medical Sciences, University of Glasgow, UK. Stillbirth refers to the birth of a baby at or beyond 24 weeks of gestation, with no signs of life or breathing after delivery.

The findings of the study appear in Diabetologia, which is the journal of the European Association for the Study of Diabetes.

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Why is it Necessary to Determine Stillbirth Risk Factors in Pregnant Diabetics?

• Women diagnosed with diabetes before pregnancy have four to fivefold higher risk of stillbirths and the risk has not reduced, while the incidence of stillbirths in general population (normal women) has decreased over time
• Traditional risk factors of stillbirths such as smoking, maternal obesity, and advanced maternal outlined in the general population remain poorly characterized for diabetes in pregnancy
• The study was thus undertaken to characterize maternal and fetal risk factors that increase the risk of stillbirths in pregnant diabetic women so that appropriate interventions can be put in place to reduce this risk

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Determining Key Factors that Increase Risk of Stillbirths in Diabetic Mothers

• The study analyzed data from the Scottish Morbidity Record 02 on babies delivered at or after 24 weeks from April 1998 to June 2016 linked to data from Scottish Care Information-Diabetes that includes women diagnosed with type 1 and type 2 diabetes before delivery
• The team analyzed possible risk factors included glycated hemoglobin (HbA1c) before and during pregnancy, maternal BMI from antenatal and diabetic check-ups, baby weight as well as factors such as hospital size and geographical location that could influence clinical care
• The study included 5392 single births delivered by 3847 women having diabetes (3778 babies delivered by 2582 women with type 1 diabetes; and 1614 babies born to 1265 women with type 2 diabetes)
• Rates of stillbirths were 16.1 per 1000 births in women with type 1 diabetes and 22.9 per 1000 births in women with type 2 diabetes, in comparison to 4.9 per 1,000 births in the general population
• Type 1 diabetic women who had stillbirths were found to have larger average blood sugar levels during all stages of the pregnancy
• In contrast, for type 2 diabetic women, pre-pregnancy blood sugar levels rather than levels during pregnancy was the key factor in increasing risk of stillbirths
• Maternal BMI was noted to be another independent risk factor for stillbirth in pregnant women with diabetes
• With regards to fetal factors, in women with type 1 diabetes, small for date babies had a higher risk of stillbirth
• For type 2 diabetic women, large for date babies increased risk of stillbirths
• Distribution of maternal age, smoking history, and number of prior pregnancies were similar in women regardless of whether the pregnancy ended in live birth or stillbirth
• Interestingly, geographical location and hospital size did not influence the rates of stillbirth suggesting that differences in clinical care did not affect stillbirth risk

The findings of the study thus suggest that maternal BMI (body mass index) and blood glucose levels are the biggest modifiable factors that increase the risk of stillbirths in pregnant women with diabetes.

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Stillbirth Risk in Male vs Female Fetuses

• Interestingly, in the study, a large proportion of stillborn infants (81%) were boys in mothers with type 2 diabetes
• The study found stillbirth rates four-fold higher in male compared to female fetuses, in women with type 2 diabetes
• Previous studies have found that male fetuses have increased risk of stillbirth by about 10% compared to female fetuses.
• However, the team caution that larger studies in different populations are needed to validate these findings

Takeaways From the Study – Reducing Stillbirth Risk

• Pre-pregnancy counseling and support to help women with type 1 and type 2 diabetes achieve optimal blood sugar control
• Educating diabetic women planning a pregnancy about the importance of achieving optimal weight to reduce the risk of complications including stillbirth
• Planning earlier delivery in diabetic mothers and babies at risk

The authors add, "However, because of potential issues with early delivery -including respiratory distress syndrome as a result of inadequate lung development - we suggest that the increased risk of neonatal morbidity needs to be more formally explored before recommendations for optimal timing of delivery are made, particularly where mothers are managing to obtain almost normal blood glucose levels."

In summary, the study conducted over 18 years and including nearly 5000 infants finds that diabetic women with high BMI and blood sugar levels have increased risk of stillbirths and addressing these issues before pregnancy can reduce the risk.

Reference:

1. Factors associated with stillbirth in women with diabetes - (https://doi.org/10.1007/s00125-019-4943-9)

Source-Medindia