Factors Influencing Cortisol Concentrations in Breastmilk and Its Associations with Breastmilk Composition and Infant Development in the First Six Months of Lactation

Abstract

Previous studies provided contradictory results regarding the influence of maternal, seasonal, and infant factors on breastmilk cortisol, and its associations with breastmilk composition and infant development. This study aimed to assess breastmilk cortisol levels at the first, third, and sixth months of lactation and evaluate the associations with maternal psychosocial, seasonal, and infant factors, breastmilk composition, and infant anthropometric and psychomotor development and temperament. Cortisol concentrations were assessed by ELISA in 24 h breastmilk samples obtained from 38 healthy mothers. Maternal psychological status was assessed by EPDS and PSS-10 and infant psychomotor development was assessed using the Children’s Development Scale (DSR). Breastmilk cortisol was 11.2 ± 6.2, 11.2 ± 4.3, and 12.7 ± 6.2 ng/mL at the first, third, and sixth months of lactation (p > 0.05), respectively. In the spring-summer season, we observed lower and higher levels of cortisol in the first and sixth months of lactation (p ≤ 0.05), respectively, but no other associations were detected regarding maternal or infant characteristics. In the third month of lactation, cortisol was related to breastmilk crude protein (β = 0.318, 0.007–0.630) and infant BMI z-score before adjustment for infant birthweight and sex (Model 2: β = 0.359, 0.021–0.697), but no other associations with breastmilk composition, infant development, or temperament were confirmed. Our results indicated that breastmilk cortisol is unrelated to maternal and infant factors and has limited influence on breastmilk crude protein, but not on infant anthropometric and psychomotor development.

Association between maternal stress and premature milk cortisol, milk IgA, and infant health: a cohort study

“…However, our findings indicated no significant association. The findings reported in our study are similar to a study of healthy term infants in whom HM cortisol had no impact on temperament or neurodevelopment ( 76 ). We also did not detect any associations between maternal stress and the infant TIMP score.…”

The association between maternal factors and milk hormone concentrations: a systematic review

“…For insulin, a lone study found no correlation between maternal age and insulin levels in human milk. Two studies explored the association between maternal age and cortisol, with both studies observing no correlation ( 28 , 41 ).…”

“…In terms of insulin, Chan et al ( 12 ) reported higher levels in Asian mothers compared to Caucasians, while another study found no association with maternal carbohydrate and energy intake ( 12 ). For cortisol, Romijn et al ( 30 ) noted lower levels in mothers seeking psychiatric consultation compared to healthy controls, and another study found no association with postpartum depression score or perceived stress ( 41 ). Pundir et al ( 41 ) observed no association between mode of delivery and cortisol levels at 3 months.…”

Bioactive Components of Human Milk and Their Impact on Child’s Health and Development, Literature Review

“…Among many of the bioactive factors, breast milk contains glucocorticoids (GCs): cortisol, cortisone, and corticosterone GCs are transferred to BM through simple diffusion [78]. In studies, increased breast milk cortisol concentrations in the first 12 weeks of an infant's life were found [79].…”

“…However, some studies found that milk cortisol is positively associated with pro-inflammatory responses to some bacteria in vitro [83]. Animal studies also suggest that cortisol may improve intestinal development in both the microbiome and intestinal immune system [78].…”