Study Design
Eligible women who were no more than 15 weeks
pregnant and who consented to participate in the
study were given a supply of placebo and asked to
return within 2 weeks. Those who returned, who
had taken at least 50% of the placebo that they were
supposed to have taken, and who still met the eligibility
criteria were randomly assigned to receive
capsules containing a combination of 1000 mg
of vitamin C (ascorbic acid) and 400 IU of vitamin
E (RRR-alpha-tocopherol acetate) or matching
placebo (mineral oil). Both the vitamin and
placebo capsules were manufactured by Strides,
which had no role in the design of the study, the
analysis or interpretation of the data, the preparation
of the manuscript, or the decision to submit
the manuscript for publication. The simple urn
method, with stratification according to clinical
center, was used by the data coordinating center
to create a randomization sequence16; boxes containing
each participant’s supply of capsules were
packaged according to this sequence. Neither the
participants nor the investigators were aware of
the treatment assignments.
Women were instructed to take the study drug
each day until they delivered their babies. The
study participants returned on a monthly basis to
return any unused study drug from the previous
month, receive a new supply of the study drug for
the coming month, report on side effects, and
have their blood pressure and urine protein level
(as assessed on dipstick testing) measured. Clinical
research staff also obtained data on neonatal
and maternal outcomes at delivery.
To determine the primary outcome and the
diagnosis of preeclampsia, deidentified medical
charts of all women with pregnancy-associated
hypertension were reviewed centrally by at least
three reviewers who were unaware of the treatment
assignments. All data were collected or abstracted
by certified research personnel at the
clinical centers and uploaded to a database that
was managed by an independent data coordinating
center, which was responsible for data analysis.
The study was approved by the institutional
review board at each clinical site and the data
coordinating center. All participants provided written
informed consent before enrollment.