在富裕国家，约90%的母亲会开始母乳喂养，但其中四分之一会在几周内放弃；过去医生认为真正的乳汁分泌不足仅占不超过5%，可近年对数百名美国和澳大利亚女性的研究显示，这一比例可能高达10%到20%。英美等地长期建议通过更频繁哺乳或使用吸奶器来增加奶量，但许多妇女仍因婴儿体重增长不足而暴露出真实的供奶不足。

研究表明，低乳量并不只是“努力不够”，而常与乳腺内乳腺细胞（lactocytes）的数量和功能有关：有些女性乳腺细胞太少，有些则功能低下。2024年《Nature Communications》鼠类实验发现，WEE1酶水平过低会破坏细胞修复机制，导致功能性乳腺细胞减少；另一些研究则怀疑胎盘损伤、感染或其他问题也可能在分娩时就埋下低供奶风险。

营养缺乏、基因变异和炎症都可能进一步降低乳汁分泌，例如锌转运相关突变与低供奶有关，慢性炎症会阻止脂肪酸进入乳腺并破坏碳水化合物合成。危险因素包括肥胖、糖尿病、自身免疫病和先兆子痫（约影响4%的女性），在一些患者中，研究显示最多有一半会出现低供奶；正在开发的乳汁钠检测等工具，可能让诊断、预测和定向治疗更快落地。

Among mothers in rich countries, about 90% start breastfeeding, but one quarter stop within a few weeks; where doctors once thought true low milk supply affected no more than 5%, recent studies of hundreds of women in the US and Australia suggest the share is more like 10% to 20%. Advice to nurse more often or use a breastpump is often insufficient, as many babies still fail to gain enough weight.

The evidence points to biology, not simply effort: some women have too few lactocytes, while others have lactocytes that function poorly. In 2024 mouse experiments reported in Nature Communications, low levels of the enzyme WEE1 disrupted repair mechanisms and left fewer functioning lactocytes, and other work suggests placental damage or infection may also raise the risk.

Nutrient shortages, gene variants, and inflammation can further reduce milk production, with obesity, diabetes, autoimmune disease, and pre-eclampsia all associated with higher risk; pre-eclampsia affects roughly 4% of women, and in some affected groups up to half may have low supply. New tests, including handheld probes that measure sodium in breast milk, may soon help diagnose the problem and guide more targeted treatment.

Source: Why many women cannot make enough breast milk

Subtitle: The causes are often beyond their control

Dateline: 5月 14, 2026 11:24 上午