Oré, B., Díaz, J. J. y Penny, M. (2011). Impacto de una intervención con grupos de mamás y bebes en el desarrollo infantil. Revista de Psicología, 29(1): 37-66.

This study evaluates the impact on child development of a group intervention with mothers and their eight-month-old babies from a marginal urban district of Lima. The groups, control and treatment, were randomized and child development was assessed before and after with the BSID-II. The intervention had a general positive impact in the children’s development, but no significant differences were found between both groups in the Mental Development Index or the Psychomotor Development Index. There was a significant effect (p < .05) in two of the BSID-II Behavioral Scale factors.