The Promotion of Breastfeeding Intervention Trial (PROBIT) is the largest cluster-randomized controlled trial ever conducted in the area of human lactation.
Breastfeeding, compared with formula feeding, has been suggested to yield benefits for children’s immune system, growth, cognitive development, and behavior. However, most research in this area has been based on animal models or observational cohort studies. The relevance of the former research to humans is unclear. Observational studies are subject to uncontrolled confounding, since breastfeeding is strongly socially patterned, and since the decision or ability to continue breastfeeding is very likely to be influenced by maternal and child characteristics.
The effects of breastfeeding can best be demonstrated in large randomized controlled trials, but it is neither possible nor ethical to randomize healthy term infants to breastfeeding versus formula feeding. It is possible, however, to randomize infants to a breastfeeding promotion intervention. The aim of PROBIT was to investigate the influence of breastfeeding on health outcomes within a randomized controlled trial, in which the two randomized arms achieved substantial differences in the duration and exclusivity of breastfeeding. The PROBIT trial is based on the long-term follow-up of healthy mothers and infants who were originally enrolled into the trial in the Republic of Belarus. Thirty-one maternity hospitals and one of their affiliated polyclinics (where children are followed for routine health care) were randomized either to a breastfeeding promotion intervention modeled on the WHO/UNICEF Baby-Friendly Hospital Initiative, or to the control arm, in which the maternity hospitals and polyclinics continued the breastfeeding practices that prevailed at the time of randomization. A total of 17,046 subjects were recruited from the 31 randomized sites, Mothers were eligible for participation if they initiated breastfeeding on admission to the postpartum ward, had no illnesses that would contraindicate breastfeeding or severely compromise its success, and had given birth to a healthy singleton infant of 37 weeks or more gestation, 2500 g or more birth weight, and Apgar score 5 or higher at 5 minutes. Study staff estimated that only 1-2% of eligible women declined participation.
Because all infants were initially breastfed, the experimental intervention was designed to increase the duration and exclusivity of breastfeeding. The intervention produced two randomized cohorts with substantially different duration and exclusivity of breastfeeding, providing a unique opportunity to test the effects of breastfeeding on health outcomes in intention-to-treat analyses. PROBIT investigators followed mothers and children for almost 20 years, and produced numerous high impact publications from intention to treat analyses demonstrating effects of the intervention on health outcomes most relevant to children. Additional observational analyses of the PROBIT cohort have yielded important insights into other early life influences on child health beyond breastfeeding. A full list of PROBIT publications can be found here.
Researchers who would like to use PROBIT data should review and complete the [PROBIT data access agreement],
then contact one of the Principal Investigators: