Introduction: The early years are a critical period of human development, and identification of biological and psychosocial factors that impact it is crucial for preventive intervention and prevention of associated disorders.Methodology: 70 mothers of preschool children were studied. 35 from a nursery and 35 from a psychiatric hospital, both in Mexico City in 2009.Risk factors were identified in the report of mothers who answered the instrument to identify risk factors and protection by Leckman on prenatal stage, labor and delivery, first five years of life and pediatric history. The study design was retrospective / prospective, cross-sectional and comparative. Statistical analysis was performed using Student's T test for independent samples. Results: There were found significant differences in the biological-individual dimension (t = -3.027, df: 68; p = 0.000) and in the context (t = -1.111, df: 66; p = 0.839), i.e., 78,6% of the clinical group have risk factors in this period of development, in contrast to the community group, whose risk factors focused on parental dimension (t = 0.915, df: 66; p = 0.839).Conclusions: It is important to identify the biological and psychosocial risk factors that affect child development, so that the health professional makes emphasis on prevention rather than rehabilitation of disorders.