Abstract
Background: The introduction of foods or fluids other than breast milk in the first few days after birth interferes with the establishment of breastfeeding. This study aimed to investigate the association of formula introduction during the first 3 days of life with maternal sociodemographic characteristics, hospital practices, and breastfeeding duration. Materials and Methods: Information from the National Survey of Demographic Dynamics, 2018, which includes 17,686 mother-baby pairs was analyzed. Mother-baby pairs were classified into categories according to breastfeeding duration: <5 months and ≥5 months. Statistical methods and a machine learning algorithm (Bayesian network, BN) were used to analyze the data. Results: In general, 3,720 (21%) mothers reported introducing formula during the first 3 days of life. A lower education level, lower sociodemographic stratum, living in a rural area, and considering oneself indigenous were factors associated with not introducing formula during the first 3 days of life. A total of 5,168 (29.2%) mother-baby pairs practiced breastfeeding for <5 months, and 12,518 (70.8%) for ≥5 months. Almost twice as many mothers who practiced breastfeeding for <5 months introduced formula during the first 3 days of life (31.7%) compared with those who practiced breastfeeding for ≥5 months (16.6%). The BN model can sufficiently predict cases with a breastfeeding duration ≥5 months (precision-recall curve area = 0.792). Discussion: Introducing formula during the first 3 days of life was associated with a shorter breastfeeding duration. BN analysis showed a probabilistic dependency between the type of delivery and variables associated with the establishment of breastfeeding.