Women’s mortality following pregnancy affected by vaginal bleeding due to threatened miscarriage: a Danish cohort study

Background Women with only pregnancy terminations or only miscarriages have an increased mortality risk. We investigated the association between vaginal bleeding (VB) in pregnancy ending in childbirth and women’s mortality. Methods We conducted a cohort study in Denmark, which included 1,354,181 women and their 3,162,317 pregnancies (1979-2017) followed through 2018. We ascertained 70,835 VB-affected pregnancies and comparators: 2,236,359 VB-unaffected pregnancies ending in childbirth; 589,697 terminations; and 265,940 miscarriages. We computed all-cause and cause-specific mortality rates per 10,000 person-years (PY) and hazard ratios (HRs) with 95% confidence intervals (CIs) using Cox proportional hazards regression adjusted for age, calendar year, preexisting conditions, and socioeconomic factors. Results There were 2,320 deaths from any cause among women following VB-affected pregnancy (mortality rate: 15.2, 95% CI: 14.6-15.9 per 10,000 PY); 55,030 deaths following VB-unaffected pregnancy (12.7, 12.6-1.28); 27,500 deaths following a termination (21.9, 21.6-22.1), and 10,865 deaths following a miscarriage (19.2, 18.8-19.6). For comparison of VB-affected vs VB-unaffected pregnancies, associations with all-cause (HR: 1.14, 95% CI: 1.09-1.19), natural-causes (HR: 1.15, 95% CI: 1.09-1.22) and non-natural causes (HR: 1.27, 95% CI: 1.08-1.48) mortality attenuated in a sensitivity analysis of pregnancies recorded in 1994-2017 (HR: 1.00, 95% CI: 0.90-1.12, HR: 0.98, 95% CI: 0.85-1.14, and HR: 1.04, 95% CI: 0.71-1.51, respectively). Contrasts with remaining comparators did not suggest increased risks of all-cause, natural, or non-natural mortality causes. Conclusions We found no evidence of an increased risk of mortality in women following VB-affected vs VB-unaffected pregnancy, termination, or miscarriage. Key Messages Previous studies mostly focused on short-term outcomes of the newborns and mothers following the vaginal bleeding-affected pregnancy. This study investigated the association between vaginal bleeding in pregnancy ending in childbirth and women’s mortality. This registry-based cohort study found no evidence of an increased risk of all-cause or cause-specific mortality from natural or non-natural causes in women following vaginal bleeding-affected pregnancy compared with vaginal bleeding-unaffected pregnancy, termination, or miscarriage