The Quality of Caregiver-Infant Interactions and Neurodevelopmental Outcomes of Infants Prenatally Exposed to Pesticides in Banana Growing Areas in Costa Rica

Background: The quality of early caregiver-child interactions is recognized as one of the strongest influences on children’s cognitive and social development, and among the most significant modifiable environmental factors. Epigenetic studies show that maternal nurturing (i.e., licking and grooming by mothers towards baby rats) promotes positive development in young rats who have experienced prenatal environmental adversity. However, no study to date has examined the impact of caregiving interactions within the context of prenatal environmental exposures. The objective of this dissertation research was to explore the relationship between the quality of caregiver-infant interactions and infant neurodevelopmental outcomes in a high-risk sample of mother-infant dyads living within poverty-stricken and pesticide-exposed banana growing areas in rural Costa Rica. This international, community-based field study was part of a larger, ongoing longitudinal study examining the developmental outcomes of infants prenatally exposed to pesticides: the Infants’ Environmental Health Study. Methods: Home visits were conducted with 94 caregiver-infant dyads living in banana-growing villages in Matina county, Costa Rica. The quality of caregiver-infant interactions was measured using a standardized observational task: the Nursing Child Assessment Satellite Training Teaching scale. One-year infant neurodevelopmental outcomes (i.e., cognitive, language, motor and social-emotional) were assessed using the Bayley-III. Multiple regression analyses examined associations between overall quality of caregiver-infant interactions and Bayley-III outcomes, adjusting for pesticide exposure and confounders. Results: Compared to U.S. Hispanic mothers, 35% of the sample had overall caregiving interaction scores at/below the 10th percentile cutoff, indicating less than optimal interactions. Quality of caregiving interactions was significantly associated with infants’ expressive language abilities (r = 0.072, p<.05). Aspects of caregiving such as stimulation and growth-fostering of infants were identified as key predictors of language outcomes. Conclusions: The results of this study suggest a positive impact of early caregiving on infant neurodevelopment for infants experiencing the double burden of environmental exposure and poverty, and highlight aspects of caregiving that can be modified to help improve outcomes of these children. The results have important implications for environmental health research and for early intervention work with this population and with other populations having environmental and concomitant risks.