Long term miscarriage-related hypertension and diabetes mellitus. Evidence from a United Kingdom population-based cohort study

BACKGROUND: Miscarriages affect up to a fifth of all pregnancies and are associated with substantial psychological morbidity. However, their relationship with cardiometabolic risk factors is not well known. Therefore, in this study we aimed to estimate the burden of cardiovascular risk factors including diabetes mellitus (type 1 or 2) and hypertension in women with miscarriage compared to women without a record of miscarriage. METHODS: A population-based retrospective cohort study was conducted using IVQIA Medical Research Data UK (IMRD-UK) between January 1995 and May 2016, an anonymised electronic health records database that is representative of the UK population. A total of 86,509, 16-50-year-old women with a record of miscarriage (exposed group) were matched by age, smoking status, and body mass index to 329,865 women without a record of miscarriage (unexposed group). Patients with pre-existing hypertension and diabetes were excluded. Adjusted incidence rate ratios (aIRR) and 95% confidence intervals (95% CI) for diabetes and hypertension were estimated using multivariable Poisson regression models offsetting for person-years follow-up. RESULTS: The mean age at cohort entry was 31 years and median follow up was 4.6 (IQR 1.7-9.4) years. During the study period, a total of 792 (IR 1.44 per 1000 years) and 2525 (IR 1.26 per 1000 years) patients developed diabetes in the exposed and unexposed groups, respectively. For hypertension, 1995 (IR 3.73 per 1000 years) and 1605 (IR 3.39 per 1000 years) new diagnoses were recorded in the exposed and unexposed groups, respectively. Compared to unexposed individuals, women with a record miscarriage were more likely to develop diabetes (aIRR = 1.25, 95% CI: 1.15-1.36; p<0.001) and hypertension (aIRR = 1.07, 95% CI: 1.02-1.12; p = 0.005). CONCLUSIONS: Women diagnosed with miscarriage were at increased risk of developing diabetes mellitus and hypertension. Women with history of miscarriage may benefit from periodic monitoring of their cardiometabolic health.