The propensity scores were estimated using logistic regression, modeling the probability of an individual being allocated to the intervention group and considering the following predictors: maternal age, educational attainment, skin color, and parity; infant weight and mode of delivery; and parental cohabitation. Significance was set at 5 % (p ≤ 0.05). All analyses were performed using the Statistical Package for the Social Sciences (SPSS), version 21.0.