Background: Prenatal exposure to p,p '-DDE is associated with impairments in motor development during the first year of life, with no related repercussions on mental or motor development at 12-30 months and with impairments in cognitive areas, but not in perceptual and motor areas at preschool age. However, its association with particular psychomotor factors, such as establishment of lateralization and spatial orientation, essential elements to the overall learning and specifically reading, writing and spelling in preschoolers, has not been independently evaluated, since cognitive and motor areas have only been explored globally. Objective: To determine the association between prenatal exposure to p,p '-DDE and the establishment of lateralization and spatial orientation in children 5 years of age. Materials and methods: Establishment of lateralization and spatial orientation was evaluated using the McCarthy Scale of Children's Abilities, with 167 children 5 years of age who participated in a birth cohort in the state of Morelos, Mexico. The information available for each child included: serum concentrations of p,p '-DDE of the mother during at least one trimester of pregnancy, mothers' intelligence quotients, stimulation at home and anthropometry. A logistic regression model was used to calculate the association between prenatal exposure to p,p '-DDE and lateralization and a multiple linear regression model was used for the association with spatial orientation. Results: A two-fold increase in p,p '-DDE in lipid base during the second trimester of pregnancy was associated with a significant reduction, 0.18 points (95% CI -0.41; 0.04, in the spatial orientation index, with no impairment in the establishment of hemispheric dominance. Attending preschool and the maternal intelligence quotient were the main determinants of spatial orientation and the establishment of hemispheric dominance. Conclusions: Prenatal exposure to p,p '-DDE may affect the 5 year old's ability to identify spatial orientation of oneself and surrounding objects. Given the observed role of attending preschool in the functions studied, early attendance in formal education might serve as a stimulation strategy for preschoolers. These preliminary results should be verified and expanded in further prospective studies with DDE. (C) 2015 Elsevier Inc. All rights reserved.
