School of Molecular Sciences, Faculty of Science, The University of Western Australia, M310, 35 Stirling Highway, Western Australia, 6009, Crawley, Australia.
Mathematics and Statistics, School of Engineering and Information Technology, Murdoch University, 90 South Street, Western Australia, 6150, Murdoch, Australia.
BMC Pregnancy Childbirth. 2020 Sep 7;20(1):516. doi: 10.1186/s12884-020-03191-5.
Concerns about reduced milk transfer with nipple shield (NS) use are based on evidence from studies with methodological flaws. Milk removal during breastfeeding can be impacted by infant and maternal factors other than NS use. The aim of this study was to control electric breast pump vacuum strength, pattern and duration across multiple study sessions to determine if NS use reduces milk removal from the breast.
A within-subject study with two groups of breastfeeding mothers (infants < 6 months) were recruited; Control Group (CG): no breastfeeding difficulties; Pain Group (PG) used NS for persistent nipple pain. Mothers completed three randomised 15 min pumping sessions using the Symphony vacuum curve (Medela AG); no NS, fitted NS, and a small NS. Sessions were considered valid where the applied vacuum was within 20 mmHg of the set vacuum. Milk removal was considered as pumped milk volume, and also percentage of available milk removed (PAMR), which is calculated as the pumped volume divided by the estimated milk volume stored in the breast immediately prior to pumping.
Of 62 sessions (all: n = 31 paired sessions) a total of 11 paired sessions from both PG (n = 03) and CG (n = 08) were valid (subset) with and without a fitted NS. Only 2 small shield sessions were valid and so all small shield measurements were excluded. Both pumped volumes and PAMR were significantly lower with NS use for all data but not for subset data. (All: Volume and PAMR median: no NS: 76.5 mL, 69%, Fitted NS: 32.1 mL, 41% respectively (volume p = 0.002, PAMR p = 0.002); Subset: Volume and PAMR median: no NS: 83.8 mL, 72%; Fitted NS: 35.2 mL, 40% (volume p = 0.111 and PAMR p = 0.045). The difference in PAMR, but not volume, was statistically significant when analysed by linear mixed modelling. A decrease of 10 mmHg was associated with a 4.4% increase in PAMR (p = 0.017).
This experimental data suggests that nipple shield use may reduce milk removal. Close clinical monitoring of breastfeeding mothers using nipple shields is warranted.
人们对使用乳头保护罩（NS）会减少乳汁转移的担忧是基于存在方法学缺陷的研究得出的。母乳喂养期间的乳汁移出可能会受到婴儿和母亲因素的影响，而不仅仅是 NS 的使用。本研究的目的是控制电动吸乳器的真空强度、模式和持续时间，以确定 NS 的使用是否会减少乳房的乳汁移出。
这项采用自身前后对照设计的研究招募了两组哺乳期母亲（婴儿<6 个月）；对照组（CG）：无母乳喂养困难；疼痛组（PG）使用 NS 缓解持续的乳头疼痛。母亲们使用 Symphony 真空曲线（Medela AG）完成了三个随机的 15 分钟抽吸疗程；无 NS、配备 NS 和小 NS。只有当应用的真空在设定真空的 20mmHg 以内时，才能认为抽吸有效。乳汁移出被认为是抽吸的乳汁量，以及可获得乳汁的百分比（PAMR），即抽吸量除以抽吸前储存在乳房中的估计乳汁量。
在 62 个疗程（全部：n=31 个配对疗程）中，共有 11 个来自 PG（n=03）和 CG（n=08）的配对疗程有效（亚组），无论是否使用配备 NS。只有 2 个小盾牌疗程是有效的，因此所有小盾牌的测量结果都被排除在外。在所有数据中，使用 NS 后抽吸量和 PAMR 均显著降低，但在亚组数据中并非如此。（全部：体积和 PAMR 中位数：无 NS：76.5mL，69%；配备 NS：32.1mL，41%（体积 p=0.002，PAMR p=0.002）；亚组：体积和 PAMR 中位数：无 NS：83.8mL，72%；配备 NS：35.2mL，40%（体积 p=0.111，PAMR p=0.045）。通过线性混合模型分析，PAMR 的差异具有统计学意义，但体积无差异。PAMR 增加 4.4%，与真空降低 10mmHg 相关（p=0.017）。
本实验数据表明，乳头保护罩的使用可能会减少乳汁移出。需要对使用乳头保护罩的母乳喂养母亲进行密切的临床监测。
