Clinical data collection instruments and database
Although the hospital was the unit of analysis at the end of the trial, individual patient information was collected at the patient level. A standard perinatal clinical history form was designed for the study in which data on obstetric history, prenatal care, labor, delivery and neonatal outcomes were registered. These data were collected directly from the clinical records and the delivery log book from each hospital. For these analyses we included all vaginal deliveries. Data for primary and secondary outcomes and on potential confounders or effect modifiers were collected.