Biomarker discovered for low breastmilk supply

Unrecognizable young mother with her crying son in sling

The discovery of a biomarker for low breastmilk supply demonstrates that low supply is real, is common and that mothers who complain of low supply are not mistaken.

Perhaps that will stop lactivists from lying about the incidence low supply and gaslighting women who have concerns about supply and fear that their infants are starving.

[pullquote align=”right” cite=”” link=”” color=”” class=”” size=””]Low breastmilk supply is NOT maternal misperception.[/pullquote]

Despite the fact that the scientific evidence shows that 15% of mothers or more can’t produce enough breastmilk to fully nourish and infant, lactation consultants, lactivist organizations and individual lactivists refuse to believe women who worry about low supply. They refuse to accept that babies are screaming from hunger. They refuse to acknowledge that infants are being injured and in some cases end up dying because of dehydration, seizures and malnutrition.

I wrote several days ago about the lactivist lie concerning infant stomach size. La Leche League UK has already modified its graphics. Did they say average newborn stomach size? Oops, they really meant average newborn intake per feeding; the newborn stomach is far larger and many infants need more than an average amount of milk per feeding.

Now comes word that low breastmilk supply may have a distinct chemical signature that should put to rest lactivists lies about supply.

Previous research found that low breastmilk production is accompanied by high breastmilk sodium, irrrespective of the mother’s diet.

High levels of sodium in breast milk are closely associated with lactation failure. One study showed that those who failed lactation had higher initial breast milk sodium concentrations, and the longer they stayed elevated, the lower the success rate. This association has subsequently been confirmed.Several possibilities have been suggested as to the cause of increased sodium levels in breast milk… It has been shown that sodium values are not affected by the mother’s diet by the method of milk expression…

A new prospective study confirms that relationship and refines it. The paper is The Relation between Breast Milk Sodium to Potassium Ratio and Maternal Report of a Milk Supply Concern by Murase et al. published this week in The Journal of Pediatrics.

The authors explain that the ratio of sodium to potassium changes as colostrum production gives way to milk production:

The ratio of breast milk sodium to potassium concentrations (breast milk Na:K) dramatically declines …  as lactation progresses through colostral, transitional, and mature milk production stages; thus, decreasing breast milk Na:K is an objective biomarker of mammary gland progress toward copious mature milk production over the first week postpartum.

The authors had two goals:

[O]ur primary objective was to determine if elevated breast milk Na:K at day 7, as an objective biomarker of lack of progress toward mature milk production, is significantly more prevalent in mothers reporting a milk supply concern, even in the context of current exclusive breastfeeding. Our secondary objective is to deter- mine whether elevated breast milk Na:K at day 7, in the context of exclusive breastfeeding, is predictive independently of stopping breastfeeding before day 60.

The authors found that high Na:K ratio in breastmilk at day 7 was associated with maternal perception of low supply and with decreased breastfeeding rates at day 60.


As demonstrated in the chart above, mothers who expressed concerned about low supply were more than twice as likely to have high Na:K ratios on day 7:

…[E]levated day 7 breast milk Na:K occurred in 42% of mothers with a day 7 milk supply concern, compared with 21% of mothers without a day 7 milk supply concern (unadjusted relative risk, 2.0; P = .008) (Table II). The unadjusted odds of elevated Na:K were 2.7 greater (95% CI, 1.3-5.9) with maternal report of milk supply concern (refer- ence = no concern, P = .01) and further increased after ad- justment for maternal ethnicity (3.4; 95% CI, 1.5-7.9; P = .003).

The risk of stopping breastfeeding by day 60 was also increased in women with high Na:K ratio on day 7:

The unadjusted odds of stopping breastfeeding by day 60 postpartum were 2.9 (95% CI, 1.1-7.8) with elevated day 7 breast milk Na:K (reference=normal breast milk Na:K; P=.04) and further increased after full adjustment for significant sociodemographic variables (3.3; 95% CI, 1.1-9.7; P = .03)

In other words, it was not a matter of flawed maternal perception; those who thought they had low supply had high Na:K ratios consistent with low supply.

The authors consider and disregard the typical lactivist denial about low supply and claims of maternal misperception:

If concerns about milk supply among exclusively breastfeeding women were primarily owing to a lack of knowledge about the signs of abundant milk production, then the expected outcome would be no difference in breast milk Na:K as compared with exclusively breastfeeding women without milk supply concerns… Instead, the observed prevalence of elevated Na:K was 2-fold greater in the mothers with milk supply concerns (42% vs 21%)… This result challenges the belief that milk supply concern in the context of exclusive breastfeeding is primarily maternal misperception. (my emphasis)

These findings have important implications:

1. Low breastmilk supply is an objective reality.

2. Low milk supply is relatively common.

3. Low milk supply is NOT maternal misperception.

4. Low milk supply is associated with a measurable biomarker that may be both diagnostic and predictive of low supply.

5. If we know early on that a mother has low supply, close watch should be kept on her infant and the threshold for formula supplementation should be low.

The bottom line is that low breastmilk supply is real, is common, and mothers who complain of low supply are not mistaken. Lactivists should be embarrassed that they ever claimed otherwise.