Routine blood tests during pregnancy for predicting future increases in risk of cardiovascular morbidity

Objective: To examine the association between routine blood tests during pregnancy and future risk of cardiovascular morbidity. Methods: The present case–control study was conducted among women who delivered at a teaching hospital in Israel between January 1, 2000, and December 31, 2012. The cohort comprised women who were subsequently hospitalized owing to cardiovascular morbidity (case group) and age-matched non-hospitalized women (control group). Blood levels of creatinine, glucose, potassium, urea, and uric acid were measured during pregnancy. Only women with at least one test result available for all five measurements were included. The relationship between upper quartile blood test values and cardiovascular hospitalization was assessed. Results: The study included 4115 women (212 in the case group and 3903 in the control group). Three measures were associated with a future risk of cardiovascular morbidity requiring hospitalization: creatinine (hazard ratio [HR] 1.86, 95% confidence interval [CI] 1.37–2.53; P<0.001); potassium (HR 1.48, 95% CI 1.09–2.01; P=0.013), and urea (HR 1.60, 95% CI 1.17–2.19; P=0.003). The number of blood test results in the upper quartile also increased such risk. The HRs for two tests and at least three tests were 1.65 (95% CI 1.06–2.56; P=0.026) and 3.32 (95% CI 2.19–5.04; P<0.001), respectively. Conclusions: Future cardiovascular morbidity was predicted by routine blood tests during pregnancy.