12 centres participated in our multicentre, randomised
controlled trial: 11 in Argentina, and one in the USA.
Trial sites included six public hospitals caring for
patients from underserved populations who often failed
to seek prenatal care, and six private hospitals that care
for women of middle and upper socioeconomic classes
who received high-quality health care. Patients were
enrolled between March 13, 2000, and Oct 1, 2001.
Enrolment did not start on the same day in all centres
during this period, but all sites finished enrolling
patients on the same date