Social Transfers for Exclusive Breastfeeding in Brazil: Protocol for a Randomized Controlled Trial.

Background: According to the World Health Organization's infant and young child feeding guidelines, infants should be exclusively breastfed for the first 6 months of life. Despite public health campaigns to increase exclusive breastfeeding (EBF) rates, socioeconomic inequities persist among low-income breastfeeding mothers, especially in countries with large wealth and health gaps, such as Brazil. Social transfer programs are initiatives that provide financial support to individuals or households to improve their well-being and reduce financial burdens. These may be conditional, requiring recipients to meet specific criteria to receive the transfer, or unconditional, in which recipients receive the transfer without prerequisites. Evidence suggests that conditional and unconditional social transfers may help increase EBF rates while addressing the economic challenges breastfeeding mothers face. A randomized controlled trial (RCT) conducted in Vientiane, Lao People's Democratic Republic, found that a social transfer program significantly improved both EBF rates at 6 months and EBF duration. Building on this study, we aim to evaluate the impact of this intervention in a different socioeconomic and cultural context.

Objective: This protocol aims to implement an RCT to assess whether conditional and unconditional social transfers improve EBF rates at 6 months postpartum for mothers in low-income communities in São Paulo, Brazil.

Methods: A prospective RCT will be conducted among 400 mothers who gave birth in the last 72 hours and plan to exclusively breastfeed. Participants will be recruited in São Paulo at the University Hospital of São Paulo and Amparo Maternal. Participants will be randomly assigned to one of the following groups: (1) control group-no social transfer; (2) intervention group 1-an unconditional social transfer at 6 months postpartum; and (3) intervention group 2-a social transfer at 6 months postpartum, conditional upon mothers' EBF. All groups will receive educational materials supporting EBF. The study will have visits at birth, 1 month, 6 months, 1 year, and 2 years and will include a questionnaire and biological collections of breast milk samples, infant fecal samples, and blood samples (finger pricks) from both the mother and infant. The main study outcomes are the prevalence of EBF at 6 months and the duration of EBF across the 3 groups, where we hypothesize higher rates of EBF among mothers in the conditional group.

Results: Recruitment began on March 6, 2024. As of September 2025, we enrolled 204 participants. Our goal is to recruit 400 mother-infant dyads by October 2025, with study visits expected to be completed by October 2027.

Conclusions: We hypothesize that the Social Transfers for Exclusive Breastfeeding in Brazil (STEBB) intervention will positively impact breastfeeding mothers in São Paulo. If successful, the program may inform national policy to enhance Brazil's existing social transfer program for new mothers.

Trial registration: ClinicalTrials.gov NCT06157697; https://clinicaltrials.gov/study/NCT06157697.

International registered report identifier (irrid): DERR1-10.2196/75796.