About 14% of pregnancies worldwide are complicated by diabetes. Having diabetes in pregnancy—whether it is gestational diabetes (GD), or preexisting type 1 and type 2 diabetes—increases the risk of perinatal complications, such as macrosomia and stillbirth. To reduce this risk, recommendations on the management of diabetes in pregnancy include dietary modifications, insulin use, ultrasound-mediated growth surveillance, and timed birth. However, the relationship between diabetes in pregnancy and birthweight and stillbirth is not well understood. One study on maternal diabetes found that the risk of stillbirth was highest in infants with birth weights >90th centile. However, the study did not differentiate between the subtypes of diabetes. The aim of this study was to determine the risk of stillbirth and birthweight in women with each subtype of diabetes in pregnancy. This was a retrospective, population-based cohort study, which included all singleton births between 24 and 42 weeks of gestation in Victoria, Australia. Perinatal and diabetes data from 2009 to 2020 were collected from national registries and databases and linked. Excluded were terminated pregnancies, women prescribed insulin without a recorded diabetes diagnosis, and children with congenital anomalies. Women were divided into diabetes subgroups: no diabetes, type 1 diabetes, type 2 diabetes, insulin-controlled GD, and diet-controlled GD. For each subgroup, the proportion of birth weights 97th centile, and the probability of stillbirths were calculated. A total of 860,042 women were included in the analysis, including 7.9% with diet-controlled GD, 3.1% with insulin-controlled GD, 0.1% with type 1 diabetes, and 0.6% with type 2 diabetes. Overall, women with diabetes of any kind had a higher proportion of infants with birth weights >97th centile, or large for gestational age (LGA), than those with no diabetes. Those with type 1 diabetes were 14 times more likely to have an LGA infant 24.4% vs. 1.6%, respectively; risk ratio (RR), 14.8; 95% CI, 13.6-16.50. Women with insulin-controlled GD (RR, 0.85; 95% CI, 0.81-0.97) and preexisting diabetes (type 1: RR, 0.23; 95% CI, 0.15-0.33; type 2: RR, 0.93; 95% CI, 0.85-1.00) were less likely to have an infant with a birthweight <10th centile. However, those with diet-controlled GD had a 14% increased risk of having an infant with birthweight <10th percentile (RR, 1.14; 95% CI, 1.12-1.16). There was a lower risk of stillbirth in women with diet-controlled GD (RR, 0.75; 95% CI, 0.64-0.89) and insulin-controlled GD (RR, 0.37; 95% CI, 0.24-0.50) as compared to those without diabetes. There was a higher risk of stillbirth observed in those with type 1 diabetes (RR, 2.38; 95% CI, 1.14-4.98) and type 2 diabetes (RR, 2.73; 95% CI, 2.01-3.72) versus those with no diabetes. Across all birthweight centiles, the probability of stillbirth was equal to or lower among women with insulin- or diet-controlled GD versus those with no diabetes. But there was a higher probability of stillbirth at all birthweight centiles in those with type 1 and type 2 diabetes. A higher risk of stillbirth was observed among women with type 1 or type 2 diabetes and LGA infants (type 1 diabetes: RR, 3.96; 95% CI, 1.23-12.76; type 2 diabetes: RR, 4.02; 95% CI, 1.71-9.47). Across all gestational ages, women with GD had a lower or equal rate of stillbirth than those without diabetes. In conclusion, GD was associated with an equivalent or decreased risk of stillbirth compared to those without diabetes across all birthweight centiles. However, preexisting diabetes was associated with an increased risk of stillbirth in all birthweight centiles and gestational ages. (Summarized from Gordon HG, Shub A, Walker SP. Maternal diabetes, fetal growth, and stillbirth risk: A population-wide retrospective cohort study from Victoria, Australia. Diabetes Care . 2025;48:1896–1903. https://doi.org/10.2337/dc25-0833)
Aaron B. Caughey (Fri,) studied this question.