Repeat postpartum magnesium sulfate administration for seizure prophylaxis: is there a patient profile predictive of...

To profile patients with hypertensive disorders of pregnancy who require reinstitution of magnesium sulfate therapy for disease exacerbation.

A prospective clinical trial enrolling gravidas with pre-eclampsia. The length of postpartum magnesium sulfate seizure prophylaxis was determined by individual patient characteristics. Patients with exacerbation of their disease after discontinuation of magnesium sulfate received a second course of magnesium sulfate lasting 24 h.

Of a total of 503 patients, 38 (7.6%) required reinstitution of postpartum magnesium sulfate therapy for an additional 24-h period. Patients with chronic hypertension complicated by superimposed pre-eclampsia were most likely to require further therapy (11/61, 18.0%), when compared with other hypertensive disorders. Additionally, patients who required reinstitution of magnesium therapy had significantly shorter gestations (32.4 +/- 4.2 weeks versus 36.3 +/- 4.2 weeks, respectively; p < 0.001), and higher mean arterial pressure during the initial magnesium course (113.2 +/- 11.2 versus 105.6 +/- 11.3 mmHg; p < 0.001).

Patients with chronic hypertension complicated by superimposed pre-eclampsia, patients delivered prior to 35 weeks' gestation and patients requiring a longer initial magnesium prophylaxis are at higher risk for the need of reinstitution of seizure prophylaxis postpartum.