BJOG

Women with type 1 diabetes face elevated preeclampsia risk

September 5, 2025

Study details: A nationwide Swedish cohort study (2003–2019) analyzed 1,689,301 singleton pregnancies, including 4,429 with pre-gestational T1DM. Glycemic control was assessed via HbA1c levels measured within ±90 days of conception. Preeclampsia was categorized by gestational age at delivery: early preterm (<34 weeks), late preterm (34–36+6 weeks), and term (≥37 weeks).

Results: Preeclampsia occurred in 16.8% of women with T1DM vs. 2.9% without diabetes (adjusted risk ratio [aRR], 4.7). Risk increased with higher HbA1c: from 11.6% (<48 mmol/mol) to 23.3% (≥76 mmol/mol). A dose-response relationship was observed, with aRRs ranging from 3.4 to 6.3 across HbA1c categories. Risk was highest for late preterm preeclampsia (aRR, 9.9), followed by early preterm (aRR, 7.2) and term (aRR, 3.5).

Clinical impact: These findings underscore the importance of optimizing glycemic control before and during early pregnancy in women with T1DM to reduce the risk of preeclampsia, particularly preterm forms associated with greater maternal and neonatal morbidity.

Source:

Holowko N, et al. (2025, August 26). BJOG. Glycaemic Control in Women With Type 1 Diabetes and Preeclampsia Risk: A Nationwide Cohort Study. https://pubmed.ncbi.nlm.nih.gov/40856153/