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

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.