Background:
There is an urgent need to understand how Primary Health Care (PHC) strategies in Latin American countries (LACs) can be developed, strengthened, and made more comprehensive, effective, and sustainable – especially given the need for cross-sectoral collaborative platforms to achieve the Sustainable Development Goals (SDGs). This study aimed to evaluate the long-term effect of PHC strategies on child mortality in Brazil, Ecuador, Mexico, and Colombia (BEMC).

Methods:
A multi-country study with a mixed ecological design was carried out. We created a longitudinal dataset (2000-2019) using secondary sources and the analysis included 5,647 municipalities with good quality of vital information. The PHC coverage was calculated and municipalities were classified into four groups: low, intermediate, high, and consolidated coverage. Dependent variables were neonatal, post-neonatal, infant, and child (under-5 and 1 to 4 years of age) mortality rates and under-5 mortality rate (U5MR) due to Primary Care Sensitive Conditions. A set of socioeconomic and health services covariables were used to adjust the models. The effect of PHC was evaluated using conditional negative binomial regression models for panel data with fixed-effects specification and the effect measure was the Rate Ratio (95% Confidence Interval).

Results:
In multivariate analysis, the consolidated PHC municipalities showed significant risk reductions of post-neonatal (27.2%), infant (13.4%), and child mortality (under-5: 18.7% and 1-4 years: 24.3%). A consolidated coverage of PHC was significantly related to lower U5MR by vaccine-preventable and sensitive conditions (RR 0.548; 95% CI 0.528-0.568), diarrhea (RR 0.442; 95% CI 0.421-0.465), anemia (RR 0.631; 95% CI 0.563-0.708), nutritional deficiencies (RR 0.556; 95% CI 0.525-0.588), and pulmonary diseases (RR 0.534; 95% CI 0.294-0.969).

Conclusion:
Despite the limitations of LACs health systems, promoting a PHC strategy has successfully contributed to improving child health. It is necessary to ensure this strategys expansion, sustainability, and equitable distribution.