Andraca, Isidora de, Paulina Pino, Alicia de La Parra, Francisca Rivera, and Marcela Castillo. 1998. “ Risk Factors for Psychomotor Development Among Infants Born under Optimal Biological Conditions ”. Revista De Saúde Pública 32 (2): 138-47. https://doi.org/10.1590/S0034-89101998000200006.