Maternal sleep and psychological status in the postpartum period are associated with functional protein alterations in breast milk:a mother-infant cohort study.

Background & Aims: Postpartum sleep disorder and mental disorders are common unpleasant conditions faced by women after delivery, and they have many adverse effects on both mothers and infants. It is unclear whether breast milk composition is affected by maternal sleep, psychological state, diet and gut microbiome. This study aims to explore the effects of these key factors on the functional protein components of breast milk.

Methods: With a prospective design, this pilot study included a total of 41 postpartum women. Breast milk and maternal faecal samples collected at 42 days and 3 months postpartum were tested by liquid chromatography-mass spectrometry and 16S RNA sequencing, respectively. Sleep state, psychological state and dietary intake data were also collected from the mothers with validated questionnaires.

Results: In the early postpartum period, sleep disorders and depression were associated with a decrease in the functional proteins in breast milk. Disordered sleep was significantly negatively correlated with α-lactalbumin (cor = -0.578, p < 0.001), osteopontin (cor = -0.522, p < 0.01) and κ-casein (cor = -0.451, p < 0.01). Depression was negatively correlated with αs1-casein (cor = -0.422, p < 0.01), β-casein (cor = -0.317, p < 0.05) and casein (cor = -0.318, p < 0.05). In 3 months postpartum, most associations were disappeared. But a positive correlation was observed between β-casein (cor = 0.414, p < 0.01), casein (cor = 0.372, p < 0.05), total protein (cor = 0.376, p < 0.05) and depression, while a positive correlation was found between total protein (cor = 0.357, p < 0.05) and disordered sleep at 3 months postpartum. Faecal microbiome data illustrated that changes in the gut microbiome at early postpartum were associated with sleep disorders/depression, but not with the diet. Furthermore, functional pathway analysis revealed metabolic regulation in the amino acid synthesis and metabolic pathways associated with specific microbes was involved in the reduction of breast milk protein.

Conclusion: Sleep disorders/depression could lead to significant changes in breast milk profiles at 42 days postpartum. Maternal gut microbiome might affect breast milk protein composition through regulating amino acid synthesis and metabolic pathways.