OBJECTIVES: To estimate the cost-effectiveness of the "Buen Comienzo" program gestation strategy, in its Family Environment modality, compared to conventional prenatal control in a third - level - complexity hospital at Medellín, 2015.

METHODS: A cost-effectiveness analysis was carried out, comparing the costs and health outcomes of two care and accompaniment modalities to pregnant mothers at the city of Medellín. The study was developed in three moments. First, the program’s effectiveness was established on a treatment and a control group. Second, a cost analysis was carried out, from the perspective of the Colombian Health System, including only direct costs. Third, a cost-effectiveness analysis was performed, based on in the average and incremental cost and effectiveness ratios of the alternatives. Deterministic and probabilistic sensitivity analyses were performed.

RESULTS: The treatment group happens to be the more cost-effective in reducing low birth weight and premature pregnancy than the control group. The cost for the treatment group were between $ 3,316,715 and $ 3,550,836 Colombian pesos (1.208 – 1.294,3 US) per Low birth weight and pre-term pregnancy avoided. It is compared to values between $ 1,187,910 and $ 1,316,333 (433 – 479 US) corresponding to the control group. The proportion of low birth weight and premature delivery was lower in the treatment group than in the control group.

CONCLUSIONS : The “Buen Comienzo” program in its Family Environment modality is a potentially cost- effectiveness strategy for early child care at the city of Medellín. It is recommended that the results obtained could be cost-effectiveness indicators to develop allocating-resources mechanisms.