• Incidence of preeclampsia
  

• Severity of preeclampsia
  
• Incidence of gestational hypertension or preeclampsia
  
• Frequency of abruptio placentae
  
• Incidence of preterm birth
  
• Incidence of small for gestational age
  
• Incidence of low birth weight infants
  
• Biomarker level correlation with preeclampsia
  

The maternal, perinatal and neonatal morbidity and mortality rates for Brazil are five to ten-fold higher than those reported for upper income countries. In Sao Paulo, 22 percent of maternal deaths are attributable to hypertensive complications of pregnancy, which ranks as the number one cause of maternal death. Recent advances in the understanding of the pathophysiology of preeclampsia suggest the possibility of antioxidant therapy for the prevention of preeclampsia. The primary hypothesis is that the joint administration of the antioxidants vitamin C (1000 mg) and vitamin E (400 IU) will reduce the incidence of preeclampsia among chronically hypertensive pregnant patients and patients with a past history of preeclampsia/eclampsia. Secondary outcomes include severity of preeclampsia; incidence of gestational hypertension; incidence of premature rupture of the membranes; incidence of preterm birth; incidence of low birth weight infants; biomarker level correlation with preeclampsia.

Study sites are high-risk obstetrical clinics in the Brazilian cities of Recife, Botucatu, Campinas, and Porto Alegre. The sample size was based on an estimated risk of preeclampsia/eclampsia of 21-25% in the control group. The study hypothesizes a 40% absolute reduction of risk of preeclampsia; early treatment withdrawal of 3%; withdrawal of consent or loss to follow-up of 10%; calculated at a 0.05 significance level with 80% power. Seven hundred thirty-four obstetric patients with chronic hypertension or preeclampsia in the prior pregnancy presenting for care between 12 weeks and 19 weeks', 6 days gestation will be randomized to a double-blinded placebo controlled trial to receive a daily dose of either vitamin E (400 International Units) and vitamin C (1000 mg) or placebo from the time of enrollment to delivery. The use of MEMS caps enables researchers to accurately track compliance.