Risk of diabetes and cardiovascular diseases in women with vaginal bleeding before 20 gestational weeks: Danish population-based cohort study

Abstract Background Women’s reproductive health is associated with cardiovascular morbidity. However, an association of vaginal bleeding (VB) in pregnancy with diabetes and cardiovascular outcomes has scarcely been investigated. Methods We conducted a population-based cohort study in Denmark (1994–2018). Using nationwide registries, among 903 327 women we identified 1 901 725 pregnancies: 39 265 ended in childbirth and were affected by VB; 1 389 285 ended in childbirth and were unaffected by VB; 333 785 ended in a termination, and 139 390 ended in a miscarriage. The outcomes were diabetes types 1 and 2, hypertension, ischaemic heart disease including myocardial infarction, atrial fibrillation or flutter, heart failure and ischaemic and haemorrhagic stroke. We computed incidence rates and hazard ratios (HRs) with 95% confidence intervals (CIs) adjusted for age, calendar year of pregnancy end, morbidities and reproductive and socioeconomic factors, using inverse probability of treatment-weighted Cox proportional hazards regression. Results In analyses of VB-affected vs VB-unaffected pregnancies, aHRs were 1.15 (1.03–1.28) for diabetes type 1, 1.19 (1.13–1.26) for diabetes type 2, 1.19 (1.14–1.25) for hypertension, 1.26 (1.16–1.37) for ischaemic heart disease, 1.21 (1.03–1.42) for myocardial infarction, 1.32 (1.14–1.51) for atrial fibrillation or flutter and 1.23 (0.99–1.52) for heart failure. aHRs were 1.41 (1.26–1.57) and 1.46 (1.23–1.72) for ischaemic and haemorrhagic stroke, respectively. When contrasting VB-affected pregnancies with terminations, aHRs were up to 1.3-fold increased for diabetes and hypertension; however, when contrasting VB-affected pregnancies with miscarriages, estimates were below or close to the null value. Conclusions Women’s risks of diabetes and cardiovascular outcomes later in life were increased following VB-affected vs VB-unaffected pregnancy or termination, but not following VB-affected pregnancy vs miscarriage.