Preexisting Diabetes in Pregnancy Doubles Stillbirth Risk, While Gestational Diabetes Appears Protective: Study Shows
Australia: Preexisting maternal diabetes is strongly associated with an increased risk of stillbirth, particularly in macrosomic infants, while gestational diabetes appears to be linked with a reduced risk, a large population-based study from Victoria, Australia, has shown. The findings, published in Diabetes Care, highlight the importance of tailored monitoring strategies for women with different forms of diabetes during pregnancy.
The research was conducted by Hannah G. Gordon from the Department of Obstetrics, Gynaecology and Newborn Health, University of Melbourne, Victoria, Australia, along with colleagues. Using data from more than 860,000 births, the team examined how preexisting diabetes and gestational diabetes influence fetal growth patterns and stillbirth risk.
The retrospective cohort study analyzed singleton births in Victoria between 2009 and 2020. Birth records were linked with perinatal and diabetes databases. This allowed researchers to assess outcomes in subgroups of women with type 1 diabetes, type 2 diabetes, and gestational diabetes, further divided into diet-controlled and insulin-controlled categories. The study evaluated birth weight distribution, probability of stillbirth by weight centile, and stillbirth rates per 1,000 pregnancies across gestational ages.
The study revealed the following findings:
- Out of 860,042 births, 100,856 (11.7%) involved diabetes in pregnancy.
- Women with diabetes delivered earlier, with a median gestational age of 38.7 weeks compared to 39.4 weeks in women without diabetes.
- Iatrogenic deliveries, including induction or cesarean section, were more common among diabetic mothers (65% vs. 44%).
- Women with preexisting diabetes had over twice the risk of stillbirth compared with those without diabetes (RR 2.68).
- The stillbirth risk was particularly high in infants above the 97th birth weight percentile, with type 1 diabetes linked to nearly a fourfold increase (RR 3.96) and type 2 diabetes showing a similar rise (RR 4.02).
- Gestational diabetes was associated with a lower stillbirth risk compared with no diabetes.
- Women with diet-controlled gestational diabetes had a 25% lower risk (RR 0.75).
- Women with insulin-requiring gestational diabetes had an even greater reduction in stillbirth risk (RR 0.37).
- The protective effect of gestational diabetes may be due to closer medical monitoring and earlier delivery.
The study concludes that preexisting diabetes continues to pose a significant risk for stillbirth, particularly in cases of fetal overgrowth, underscoring the need for intensive monitoring of high-birth-weight infants in this group. Meanwhile, the reduced stillbirth risk in gestational diabetes highlights how proactive management and careful obstetric intervention can improve outcomes.
"By distinguishing the contrasting risks of preexisting and gestational diabetes, the research provides important insights for clinicians in tailoring care strategies to reduce adverse pregnancy outcomes," the authors wrote.
Reference:
Gordon HG, Shub A, Walker SP, Hiscock RJ, Atkinson J, Tong S, Hastie RM, Lindquist AC, Pritchard NL. Maternal Diabetes, Fetal Growth and Stillbirth Risk: A Population-Wide Retrospective Cohort Study From Victoria, Australia. Diabetes Care. 2025 Sep 3:dc250833. Doi: 10.2337/dc25-0833. Epub ahead of print. PMID: 40902109.
