Division of Neonatology, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, 10700, Thailand.
Division of Clinical Epidemiology, Department of Health Research and Development, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
Int Breastfeed J. 2023 Nov 23;18(1):63. doi: 10.1186/s13006-023-00599-5.
Human hindmilk contains higher concentrations of fat than foremilk and is more desirable for growth in preterm infants who can tolerate limited volumes of breastmilk. There is currently no clear demarcation between foremilk and hindmilk. This study characterized the change in breastmilk's fat content from the start to end of milk flow and defined this demarcation.
Mothers of infants born at ≤ 32 weeks gestational age and ≥ 14 days after childbirth in a University hospital in Bangkok, Thailand between July, 2011, and April, 2012 were included in this cross-sectional study. Breastmilk samples were sequentially collected from the start to end of milk flow in 5-mL aliquots using breast pumps. The fat content of each aliquot from each breast was determined through creamatocrit. The average creamatocrit of foremilk and hindmilk were compared in predefined foremilk to hindmilk ratios of 20:80, 25:75, 33:67, and 50:50. Creamatocrit of the first and last aliquots were compared for mothers who expressed low- (≤ 25-mL per breast) and high-volumes (> 25-mL per breast) of breastmilk.
Of the 25 mothers enrolled, one was excluded due to unsuccessful creamatocrit measurement. The last aliquot of breastmilk had a significantly higher creamatocrit than the first from the same breast (median [interquartile range] of 12.7% [8.9%, 15.3%] vs. 5.6% [4.3%, 7.7%]; test statistic 1128, p < 0.001). Mean creamatocrit in hindmilk portions (9.23%, 9.35%, 9.81%, and 10.62%, respectively) was significantly higher than foremilk portions (6.28%, 6.33%, 6.72%, and 7.17%, respectively) at all predefined ratios. Creamatocrit increased by 1% for every 10% incremental increase in expressed breastmilk volume until the breast was emptied. Low-volume mothers had a significantly higher creamatocrit in the first aliquot compared with high-volume mothers (U = 437, p = 0.002). No significant difference in breastmilk volume was observed between mothers with and without breastfeeding experience.
Fat content in breastmilk increased on an incremental basis. More fluid definitions of foremilk and hindmilk should be adopted. Mothers should prepare their breastmilk into aliquots based on the required feeding volume of their infant. Hindmilk aliquots can be prioritized over foremilk aliquots to ensure infants obtain optimal caloric intake.
相较于前奶，人乳的后奶含有更高浓度的脂肪，对于能够耐受有限量母乳的早产儿而言，其更有利于生长。目前，前奶和后奶之间没有明确的界限。本研究旨在描述从泌乳开始到结束时母乳中脂肪含量的变化，并定义这个界限。
2011 年 7 月至 2012 年 4 月，在泰国曼谷的一家大学医院中，纳入胎龄≤32 周且产后≥14 天的婴儿的母亲，进行这项横断面研究。使用吸乳器以 5-mL 等分液的方式从泌乳开始到结束，顺序采集母乳样本。通过乳脂计测定每个等分液中每份母乳的脂肪含量。比较了不同预定义的前奶与后奶比例（20:80、25:75、33:67 和 50:50）下，左右乳房的前奶和后奶的平均乳脂计读数。比较了左右乳房泌乳量低（≤25-mL/ 侧）和高（＞25-mL/ 侧）的母亲的第一和最后等分液的乳脂计读数。
在纳入的 25 位母亲中，1 位因乳脂计测量不成功而被排除。同一乳房的最后等分液的乳脂计读数明显高于第一等分液（中位数[四分位间距]为 12.7%[8.9%，15.3%]比 5.6%[4.3%，7.7%]；检验统计量 1128，p<0.001）。所有预定义比例下，后奶部分的平均乳脂计读数（分别为 9.23%、9.35%、9.81%和 10.62%）均显著高于前奶部分（分别为 6.28%、6.33%、6.72%和 7.17%）。随着母乳挤出量每增加 10%，乳脂计读数增加 1%，直到乳房排空。与泌乳量高的母亲相比，泌乳量低的母亲的第一等分液乳脂计读数明显更高（U=437，p=0.002）。有和没有母乳喂养经验的母亲之间的母乳量无显著差异。
母乳中的脂肪含量呈递增式增加。应该采用更具流动性的前奶和后奶定义。母亲应根据婴儿的所需喂养量将母乳分装。为了确保婴儿获得最佳热量摄入，应优先选择后奶等分液，而非前奶等分液。
