Long-Term Breastfeeding and Neurodevelopment at 14 Months: Which Factors Could Explain This Relationship?

Abstract

ISEE-0740 Background and Objective: Although breastfeeding increases organochlorine transfer to infants, it has been found to be beneficial for the neurodevelopment of the child. Several mechanisms have been proposed to explain these benefits. This study aims to assess the role of three possible mediators: long-chain polyunsaturated fatty acids (LC-PUFAs) levels in colostrum, mother-child attachment, and maternal factors such as intelligence quotient (IQ), education level, and social class in the link between breastfeeding and children’s neurodevelopment at 14 months. Methods: In the Spanish INMA (Environment and Childhood)-Sabadell birth cohort, 657 women were recruited during the 1st trimester of pregnancy. At 14 months, mental and psychomotor development with Bayley Scales of Infant Development was assessed in 561 children, as well as mother-child attachment and maternal IQ. Full breastfeeding was defined as exclusive breastfeeding in addition to infrequent feeds of water or juice. Information about maternal education level and social class were obtained by questionnaire. Maternal organochlorine levels during the 1st trimester of pregnancy were measured by GC-MS and LC-PUFAs in 352 colostrum samples by fast gas chromatography. Multivariable linear regression models were performed. Results: Only very long-term full breastfeeding (> 6 months) was associated with higher infant mental score (6.44 points, 95% confidence interval 1.79–11.08). At smaller durations there was no trend. No relationship was found with psychomotor development scores, although α-linolenic/linoleic acid ratio, maternal education, IQ, and social class were associated with mental development scores (P-value < 0.02). Adjustment for these variables did not confound the association between long-term full breastfeeding and mental development score. Mother-child attachment score and maternal organochlorine levels were not associated with development scores. Conclusion: Both the lack of any association for breastfeeding less than 6 months and the lack of any confounding in the effect of long breastfeeders suggest that non measured social or environmental variables may explain higher mental development among very long breastfeeders rather than breastfeeding itself.