OBJECTIVE: To establish the association between increased levels of D-dimer and severity of pre-eclampsia.METHODS: A nested, prospective cohort, analytical case-control study was conducted among women with pre-eclampsia between March 2017 and March 2018. Inclusion criteria were age over 18 years, gestational age of more than 20 weeks, a single pregnancy with a living fetus, and a diagnosis of pre-eclampsia. D-dimer was measured by immunoturbidimetry at the time of diagnosis of pre-eclampsia, applying cut-off points adjusted for gestational age. Statistical analysis involved unconditional logistic regression for the association of elevated D-dimer with severe pre-eclampsia adjusted by confusion variables.RESULTS: There were 132 patients with pre-eclampsia, of which 44 were classed as controls and 88 were classed as having severe pre-eclampsia (case group). Cohort characteristics included: age between 18 and 45 years (mean 28.0 ± 6.3 years); presence of gestational hypertension (10.6%), chronic arterial hypertension (9.0%); and gestational diabetes (5.3%). In the case group, levels of D-dimer were significantly higher than in controls (19.3% vs 2.3%, odds ratio [OR] 10.30, 95% confidence interval [CI] 1.32-80.14, P=0.004) as well as significant in the unconditional logistic regression model adjusted for maternal age, parity, gestational age, and comorbidities (OR 10.02, 95% CI 1.28-78.68, P=0.028).CONCLUSION: Elevated levels of D-dimer and severe pre-eclampsia are strongly associated, reinforcing evidence that one of the physiopathologic bases of the condition is the activation of fibrinolysis and the coagulation system.