Objective: to measure the effect of an infant stimulation therapy (auditory, tactile, visual and vestibular) on the adaptation to postnatal life of the mother-child dyad. Method: an experimental and blind study composed of 120 dyads of first-time mothers and full-term newborns, who practiced breastfeeding. The follow-up was conducted during the first five weeks of life and the evaluation was carried at two different times. Results: the adaptive capacity was measured in two modes. The physiological adaptive mode (activity and exercise and neonatal nutrition) and the interdependence adaptive mode (appropriate affection and proper development); and statistically significant differences were found in favor of the experimental group. Regression models that show the collaborative relationship between mother and child, and their reciprocity in the process of adaptation were proposed. Conclusion: the early stimulation is a therapy with bidirectional effect, because it has favorable effects on the person who administers it; promotes health and prevents illness in the process of adaptation to birth; especially in contexts of vulnerability. It is recommended its teaching to mothers and its application in the home environment. This study was registered in the Australian New Zealand Clinical Trial Registry (ANZCTR) under protocol number: ACTRN12617000449336.