IntroductionAlthough the primary function of a woman's breast is milk synthesis, only a few studies have evaluated the relationship between breast size and human milk composition, showing equivocal results. This study aims to test if breast size during fully established lactation is related to energy density and content of macronutrients in human milk.Materials and MethodsMothers of healthy, born‐on‐term infants at stage III of lactogenesis (N = 137) provided breast milk samples. Milk composition was analyzed using midinfrared transmission spectroscopy. The breast size index was calculated by dividing the breast by the circumference below the breast.ResultsStepwise forward linear regression showed a negative association between breast size index and lactose concentration in breast milk (β = −.242, p = .003). The final model, which includes breast size index, feeding frequency, and maternal energy intake together explained around 13% of the variance in breast milk lactose content (R2adj = .126, p < .001). No statistically significant relationship was found between breast size index and milk's energy density, protein, and fat content.ConclusionThis is the first study that shows a negative relationship between breast size during fully established lactation and lactose concentration in milk in a large sample size. No relationship between other macronutrients and breast size indicates that large breast size is not necessary for adequate milk production; however, it may contribute to an altered lactose concentration.

中文翻译：

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哺乳期妇女的乳房大小和母乳中常量营养素的含量

简介虽然女性乳房的主要功能是乳汁合成，但只有少数研究评估了乳房大小与母乳成分之间的关​​系，结果模棱两可。本研究旨在测试完全哺乳期间的乳房大小是否与母乳中的能量密度和大量营养素的含量相关。 材料和方法处于泌乳第三阶段的健康足月婴儿的母亲（氮= 137）提供母乳样本。使用中红外透射光谱分析牛奶成分。乳房大小指数的计算方法是将乳房除以乳房下方的周长。结果逐步前向线性回归显示乳房大小指数与母乳中的乳糖浓度呈负相关（β= −.242,p=.003）。最终模型包括乳房大小指数、喂养频率和母亲能量摄入，共同解释了母乳乳糖含量约 13% 的差异（右2形容词= .126,p< .001)。乳房大小指数与牛奶的能量密度、蛋白质和脂肪含量之间没有发现统计学上的显着关系。结论这是第一项大样本研究，表明完全哺乳期间乳房大小与牛奶中乳糖浓度之间存在负相关关系。其他常量营养素与乳房大小之间没有关系，表明乳房大小对于充足的产奶量来说并不是必要的；然而，它可能会导致乳糖浓度改变。