The effect of between-breast differences on human milk macronutrients content

Area of Science:

• Human milk composition
• Lactation biology
• Nutritional science

Background:

• Limited research exists on how maternal handedness and preferential breastfeeding side influence human milk (HM) macronutrient concentrations.
• Understanding these factors is crucial for assessing variations in milk composition.

Purpose of the Study:

• To investigate the impact of maternal handedness, breast size, and dominant breastfeeding side on the macronutrient content of human milk.
• To test the hypothesis that these factors do not affect macronutrient levels in HM.

Main Methods:

• Recruited 57 lactating mothers for the study.
• Analyzed human milk (HM) macronutrients using infrared transmission spectroscopy after mid-manual expression.
• Collected data on maternal handedness, breast size, and reported dominant breastfeeding side.

Main Results:

• No statistically significant differences in macronutrient content (fat, carbohydrate, protein, energy) were found between the right and left breasts.
• Maternal handedness, breast size asymmetry, or dominant breastfeeding side did not affect the measured macronutrient levels in HM.
• Breast size asymmetry was reported by 22 mothers, with the dominant side often being the larger breast.

Conclusions:

• Macronutrient composition of mid-expression human milk is not influenced by maternal handedness.
• Breast size and dominant breastfeeding side do not significantly alter the macronutrient profile of human milk.
• These findings suggest consistency in HM macronutrient content regardless of maternal laterality or feeding preferences.