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Stillbirth Risk In Pregnant Women With Diabetes

Sep 3, 2019
 
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Joel John, Pharm.D. Candidate, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences

Body mass index and glucose control play a role in the higher stillbirth risk for pregnant women with diabetes.  

Stillbirth is when a baby has died in the womb after being alive for at least 24 weeks. Women who have hypertension or diabetes have more than twice the risk of having a stillbirth. Not much is known about the mechanism of how this happens at an increased rate in pregnant women with diabetes, which is what this study is trying to shed some light on.

 

This was a retrospective cohort study that used data from various databases, including maternity records from the Scottish Morbidity Record 02 database and the Scottish Care Information-Diabetes, which is the Scottish national database for diabetes. The study looked at mothers with type 1 and type 2 diabetes from April 1998 to June 2016. In a trial of this nature, many different factors need to be measured and considered. Birth Weight z score was calculated throughout the pregnancy so it can be compared to what is deemed as a safe weight for the baby. HbA1c values were also measured throughout the pregnancy. Furthermore, the BMI of the mother was also measured throughout the pregnancy process.

There was a total of 5,392 mothers that were included in this study. 229 had to be excluded for various reasons. Some of these reasons included a diabetes diagnosis that was not type 1 or type 2, sex of infant not identified, unknown gestational age during the time of delivery, and pregnancies that resulted in twin infants. Of the 5,392 babies that were included in the study, 3,778 had mothers with type 1 diabetes and 1,614 had mothers with type 2 diabetes. The rate of stillbirth was 16.1 per 1000 births in mothers who had type 1 diabetes, while the stillbirth rate was 22.9 per 1000 births in women who had type 2 diabetes.

In pregnant women with type 1 diabetes, it was noted that the mean pre-pregnancy HbA1c was roughly 1% higher in the women whose pregnancy ended in stillbirth compared to the women with type 1 diabetes whose pregnancies did not end in stillbirth. Stillborn babies were typically born 2.8 weeks earlier than liveborn babies. Roughly 38% of stillbirths happened at term compared to 63% of the live births that happened at term.

Women with type 2 diabetes whose pregnancies ended in stillbirth usually had a higher pre-pregnancy BMI compared to the mothers with type 2 diabetes who had living babies. Another observation was that the stillborn infants in women with type 2 diabetes were usually more likely to be male. In women with type 2 diabetes, stillborn babies were generally delivered 3 weeks earlier compared to liveborn babies. Infants were most likely to become stillborn if their birth weight was less than the 10th percentile or greater than the 95th percentile.

Another trend that was seen in women with type 1 diabetes was that women who had a shorter duration of diabetes along with a lower BMI were associated with stillbirth. There was also a significant correlation between stillbirth and higher pre-pregnancy HbA1c levels in women with type 1 diabetes. Higher BMI and HbA1c resulted in more stillborn in women with type 2 diabetes.

Even though the entire process of how an infant becomes a stillborn is not fully known, there are certain stillbirth risk factors that can certainly play a role. Some of these risk factors that can be changed include a pregnant mother’s glucose level and body mass index.

Practice Pearls

  • A new study further cemented the relationship between pregnant women with diabetes and having a stillborn infant.
  • Although there are many risk factors that play a role in this occurrence, the main modifiable risk factors are body mass index and glucose control. It is important to educate pregnant women about the importance of these risk factors and what it could mean for their offspring.
  • How a stillbirth can be prevented is still being researched to this day, but this study helps with the overarching goal of finding ways to pinpoint the exact causes of this tragedy.

 

Mackin, S.T., Nelson, S.M., Wild, S.H. et al. Diabetologia (2019). https://doi.org/10.1007/s00125-019-4943-9

 

Joel John, Pharm.D. Candidate, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences