Socio-economic inequalities in the effect of public policies and the COVID-19 pandemic on exclusive breastfeeding in Chile.

OBJECTIVE: To assess the impact of the addition of 12 maternity leave (ML) weeks (2011), a pay for performance (P4P) exclusive breastfeeding (EBF) promotion strategy (2015), and the COVID-19 pandemic in EBF inequalities in Chile. STUDY DESIGN: Interrupted time-series analyses (ITSAs). METHODS: Aggregated national EBF data by municipality and month were collected from 2009 to 2020. We assess the impact of the three events in EBF inequalities using two procedures: 1. ITSA stratified by municipal SES quintiles (Q1-Q5); 2. Calculating the EBF slope index of inequality (SII). RESULTS: The EBF prevalence was higher in lower SES municipalities before and after the three time-events. No impact in EBF inequalities was observed after the extended ML. The P4P strategy increased EBF at six months in all SES quintiles (effect size between 4% and 5%), but in a higher level in poorer municipalities (SII: -0.36% and -1.05%). During COVID-19, wealthier municipalities showed a slightly higher EBF at six months prevalence (SII: 1.44%). CONCLUSION: The null impact of the extended ML in EBF inequalities could be explained by a low access to ML among affiliated to the public health system (20%). The P4P strategy includes multiple interventions that seemed effective in increasing EBF across all SES quintiles, but further in lower quintiles. The restrictions in healthcare access in poorer municipalities could explain EBF inequalities during COVID-19.