Association between preterm delivery and subsequent maternal risk of hypertension and type 2 diabetes mellitus in a UK population-based retrospective cohort study

OBJECTIVES: Women with a history of preterm delivery (PTD) are at higher risk of developing cardiovascular diseases (CVD) later in life. However, it is not well established whether PTD is associated with CVD risk factors, hypertension and type 2 diabetes mellitus (T2DM). Therefore, in this study, we examined the associations between PTD compared with term delivery and subsequent risk of hypertension and T2DM. DESIGN: Retrospective matched population-based open cohort study. SETTING: Clinical Practice Research Datalink GOLD data in the UK. PARTICIPANTS: A total of 3335 18–49-year-old women with preterm delivery were matched by age and region to 12 634 without a record of preterm delivery. PRIMARY OUTCOME MEASURES: Outcomes of interest were newly diagnosed hypertension or T2DM at least 6 months after delivery. During the study period (January 2000–December 2019), hypertension or T2DM events in the medical records of women with (exposed) and without (unexposed) preterm delivery were compared. HR and 95% CI were estimated using Cox proportional hazards models adjusted for potential confounders. RESULTS: Over a median follow-up period of 5.11 (IQR 2.15–9.56) years, the HRs for hypertension in women who delivered preterm compared with women who delivered at term were 1.42 (95%CI 1.09 to 1.80) and 1.18 (95%CI 0.90 to 1.56) in the unadjusted and adjusted models, respectively. For T2DM, over a median follow-up period of 5.17 (IQR 2.18–9.67) years, the HRs in women who delivered preterm compared with those who delivered at term were 1.67 (95%CI 1.12 to 2.48) and 1.10 (95%CI 0.72 to 1.68) in the unadjusted and adjusted models, respectively. CONCLUSION: We found no independent effect of preterm delivery on risk of hypertension or type 2 diabetes in this study. While significant associations were observed in unadjusted analyses, associations were lost after adjustment and may be attributable to other reproductive complications. Additional studies are needed to confirm these findings.