Human milk immune factors, maternal nutritional status, and infant sex: The INSPIRE study

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Date

2023

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Volume Title

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Wiley Periodicals LLC.

Abstract

Abstract Objectives: Breastfeeding is an energetically costly and intense form of human parental investment, providing sole-source nutrition in early infancy and bio active components, including immune factors. Given the energetic cost of lactation, milk factors may be subject to tradeoffs, and variation in concentra tions have been explored utilizing the Trivers-Willard hypothesis. As human milk immune factors are critical to developing immune system and protect infants against pathogens, we tested whether concentrations of milk immune factors (IgA, IgM, IgG, EGF, TGFβ2, and IL-10) vary in response to infant sex and maternal condition (proxied by maternal diet diversity [DD] and body mass index [BMI]) as posited in the Trivers-Willard hypothesis and consider the application of the hypothesis to milk composition. Methods: We analyzed concentrations of immune factors in 358 milk samples collected from women residing in 10 international sites using linear mixed effects models to test for an interaction between maternal condition, including population as a random effect and infant age and maternal age as fixed effects. Results: IgG concentrations were significantly lower in milk produced by women consuming diets with low diversity with male infants than those with female infants. No other significant associations were identified. Conclusions: IgG concentrations were related to infant sex and maternal diet diversity, providing minimal support for the hypothesis. Given the lack of asso ciations across other select immune factors, results suggest that the Trivers Willard hypothesis may not be broadly applied to human milk immune factors as a measure of maternal investment, which are likely buffered against pertur bations in maternal condition

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Research Article

Keywords

Lactation, Human milk, Infant, Nutritional status

Citation

Caffé, B., Blackwell, A., Fehrenkamp, B. D., Williams, J. E., Pace, R. M., Lackey, K. A., Ruiz, L., Rodríguez, J. M., McGuire, M. A., Foster, J. A., Sellen, D. W., Kamau-Mbuthia, E. W., Kamundia, E. W., Mbugua, S., Moore, S. E., Prentice, A. M., Kvist, L. J., Otoo, G. E., Pareja, R. G., … Meehan, C. L. (2023). Human milk immune factors, maternal nutritional status, and infant sex: The INSPIRE study. American Journal of Human Biology, e23943.

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