Changes in human milk composition during the initiation of lactation

Area of Science:

• Human Physiology
• Lactation Biology

Background:

• Understanding the biochemical changes in mammary secretions during lactation initiation is vital.
• Distinguishing between lactation initiation and maintenance is key for maternal and infant health.

Purpose of the Study:

• To investigate the progressive changes in mammary secretion constituents during lactation initiation.
• To compare secretion composition in breastfeeding and non-breastfeeding women.

Main Methods:

• Analysis of metabolites (lactose, glucose, urea), electrolytes (sodium, potassium, chloride, calcium, magnesium), and proteins (total protein, alpha-lactalbumin, lactoferrin, albumin, IgA, IgG, IgM).
• Measurement of mammary secretion samples (0.5-5.0 ml) from late pregnancy through the postpartum period.
• Comparison of secretion composition between breastfeeding and non-breastfeeding women.

Main Results:

• Colostrum in late pregnancy showed higher protein and lower metabolite concentrations than mature milk.
• Electrolyte differences observed: higher sodium, chloride, magnesium; lower potassium, calcium in colostrum.
• Lactation initiation occurred in two phases: limited secretion pre-partum and lactogenesis 32-40 hours post-delivery.

Conclusions:

• Mammary secretion composition changes significantly during lactation initiation, with distinct phases.
• Breastfeeding is essential for maintaining lactation but not its primary initiator.
• Non-breastfeeding women exhibit temporary lactation changes followed by involution.