Introduction. Breastfeeding (BF) has challenges from preparation, birth, first hour of life (FHL), protection of mothers in hospital, support from counselors and relatives. Exclusive BF in Colombia is 36.1% (1 month) and in Envigado municipality reached 3.1 months, in 2015. Objective. Compare the practice of BF and factors associated with planning of gestation, onset, type and total duration of BF in young mothers (YW) and adults (AW) of the Municipality of Envigado, Antioquia Department, Colombia. Material and methods. Quantitative, observational study, with probability sampling. From a universe of 3,540 newborns, 288 lactating mothers were selected. Variables associated with health services, practices and times of BF were studied. SPSSv22 was used for data analysis. Study approved by the ethics committee of the CES University. Results. Delivery of the baby to the immediate mother or FHL (83%), favors early BF (74%). Exclusive BF (4.6 months) and total BF (12.6 months) were similar in YW (<27 years) and AW (>= 27 years). In YW, having the baby hospitalized (p = 0.00), the number of children (p = 0.04) and a planned pregnancy (p = 0.02) predict BF in FHL, exclusive and total BF. In AW, having the minor hospitalized (p = 0.01), occupation and counseling predict BF in FHL, exclusive and total. The main predictor of exclusive (p = 0.02) and total (p = 0.01) BF is BF counseling. Discussion. BF counseling is the main strategy for the support, promotion and maintenance of BF, which is reflected in the high prevalences of this essential practice. Conclusions. Advice on BF from pregnancy is the main factor that predicts the practice of exclusive and total BF. The hospitalization of the neonate in the postpartum period and type of delivery significantly influences skin-to-skin contact and BF in the first hour of life.