In an effort to better define preeclamptic women at risk of eclampsia, we examined the predictive value of maternal demographic characteristics and admission maternal laboratory values for the risk of subsequent development of eclampsia in preeclamptic women, who were not receiving magnesium sulfate during hospitalization. The decision to use magnesium sulfate prophylaxis was at the discretion of the treating physician. Preeclamptic women admitted throughout a 3-year period and treated with a protocol exempting magnesium sulfate therapy were retrospectively included (n = 497). Maternal data at admission were recorded and analyzed. Eight women developed an eclamptic seizure during subsequent hospital follow-up. Logistic regression models were used to assess the independent predictive role of each variable on the development of eclampsia. Lower serum fibrinogen values, increased leukocyte counts, and increased diastolic blood pressure at admission were independent predictors of a subsequent in-hospital eclamptic seizure. An initial diastolic blood pressure >= 120 mm Hg, blood leukocyte count > 16,000/mu L, and serum fibrinogen value < 450 mg/dL were associated with a 25.4-, 7.1-, and 26.6-fold increased risk of eclampsia, respectively. We conclude that marked leukocytosis and diastolic blood pressure increment might precede the development of eclampsia. Serum fibrinogen concentrations > 450 mg/dL seem to be protective for eclampsia. The association between inflammation and eclampsia merits further investigation.