Objective To systematically analyze the dynamic change patterns of human milk oligosaccharides (HMOs) across four critical lactation stages (colostrum, transitional milk, 6-month milk, and 12-month milk) in mothers with both Secretory and Lewis positive phenotypes (Se⁺Le⁺) from Beijing, so as to provide a scientific reference for optimizing the stage-specific design of infant formula.

Methods A total of 136 breast milk samples were consecutively collected from 34 healthy Se⁺Le⁺ mothers from postpartum day 2 up to 12 months postpartum. High-performance liquid chromatography-mass spectrometry (HPLC-MS) was used to quantify 19 major HMOs with detection rates exceeding 70%. The concentration trends and internal correlations of these HMOs across different lactation stages were analyzed.

Results The concentrations of most HMOs decreased with lactation period advanced, 17 HMOs concentration decreased among the 19 HMOs. Among neutral fucosylated HMOs, the concentration of 2'-Fucosyllactose (2'-FL) continuously decreased starting from the colostrum stage, while the concentration of 3-Fucosyllactose (3-FL) increased with the progression of lactation, exhibiting a complementary pattern. However, among neutral non-fucosylated HMOs, the concentrations of lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT) decreased with prolonged lactation period, but their ratio remained stable throughout the whole lactation. In acidic HMOs, the concentration of 3'-Sialyllactose (3'-SL) fluctuated, exhibiting a pattern of initially decreasing and then slightly increasing during later lactation stages, while the concentrations of 6'-Sialyllactose (6'-SL) and Sialyllacto-N-tetraose c (LSTc) decreased consistently, as well as the concentration of Disialyllacto-N-tetraose (DSLNT) decreased with prolonged lactation. Spearman correlation analyses revealed a strong negative correlation between 2'-FL and 3-FL concentrations throughout the whole lactation (colostrum: r_s=-0.35, P<0.05; transitional milk: r_s=-0.34, P<0.05; 6-month milk: r_s=-0.31, P=0.073; 12-month milk: r_s=-0.49, P<0.05). The correlation between Lacto-N-fucopentaose Ⅰ (LNFP-Ⅰ) and Lacto-N-fucopentaose Ⅱ (LNFP-Ⅱ) concentrations only showed negatively 12-month milk (r_s=0.36, P<0.05). In the neutral non-fucosylated HOMs, the concentration of LNT and LNnT exhibited a positive correlation in most lactation periods (colostrum: rs=0.71, P<0.05; transitional milk: r_s=0.67, P<0.05; 12-month milk: r_s=0.70, P<0.05). In the acidic HOMs, the concentration of DSLNT was positively correlated with LSTb concentration in early lactation (colostrum: r_s=0.38, P<0.05;transitional milk: r_s=0.57, P<0.05), whereas the concentration of 3′-SL and 6′-SL became positively correlated in later lactation.

Conclusion The HMO composition in Se⁺Le⁺ mothers from Beijing undergoes characteristic and programmed dynamic changes across lactation stages. The longitudinal data from this study can provide crucial information for enriching the Chinese population’s HMO database and offer a scientific basis for developing more precise, stage-specific infant formulas.