Cardiometabolic health during early adulthood and risk of miscarriage: a prospective study

Background: Several studies have found that women who are overweight or obese have an increased risk of miscarriage. There is also some evidence of associations of other aspects of cardiometabolic health, including blood pressure and lipids, with miscarriage risk, although these have not been examined to the same extent as body-mass index (BMI). Methods: Our objective was to investigate the risk of miscarriage according to pre-pregnancy cardiometabolic health. We examined pre-pregnancy levels of BMI, blood pressure, fasting insulin and metabolites profile at age 18 and risk of miscarriage by age 24. The study included adult female offspring in the Avon Longitudinal Study of Parents and Children with a pregnancy between 18 and 24 years of age (n=434 for BMI and blood pressure; n=265 for metabolites). We used log-binomial regression to calculate adjusted associations between cardiometabolic health measures and miscarriage. Results: The overall risk of miscarriage was 22%.  The adjusted relative risks for miscarriage were 0.96 (95% CI: 0.92-1.00) for BMI (per unit increase), 0.98 (0.96-1.00) for systolic blood pressure, and 1.00 (0.97-1.04) for diastolic blood pressure (per 1 mmHg increase).  Total cholesterol, total lipids and phospholipids in HDL-cholesterol were associated with increased likelihood of miscarriage, but none of the p-values for the metabolites were below the corrected threshold for multiple testing (p-value ≤0.003). Conclusions: Our findings indicate no strong evidence to support a relationship between pre-pregnancy cardiometabolic health and risk of miscarriage in young, healthy women who became pregnant before age 24. Future studies are necessary that are able to evaluate this question in samples with a wider age range.