What causes Dysphoric Milk Ejection Reflex?

What the research doesn't tell us, so far

There is a lot that we don't know about DMER. We do know it is an embodied, emotional, distressed response to a specific, time-limited and repeated physiological event (milk letdown). We don't know what causes it. The definition of DMER remains poorly understood by many providers, and may be missed. However, there is also a risk that with growing awareness of DMER, in a context of globally high levels of overdiagnosis and overtreatment of breastfeeding women, that this diagnosis is increasingly promoted by high profile educators and applied in a way that is not consistent with emergent research.

A woman's emotional or physical experience of distress during breastfeeding must always be believed, and taken very seriously by her providers. There is also no benefit in contesting a DMER diagnosis, if the diagnosis has been given inappropriately by someone else but the woman finds the diagnosis helpful as validation of her distress or difficulty. What matters is the quality of clinical support she receives in response to her experience.

From the NDC evolutionary perspective

• DMER is likely to arise from, and be affected by, multiple factors, depending on each individual woman.

• Weaning the infant from the breast is a healthy response to DMER, if DMER is not responding to interventions.

• Studies of DMER so far, like most breastfeeding research, don't take into account underlying and unidentified clinical problems, due to our health system blind spots. It makes sense that there are high levels of aversive sensations and emotions in breastfeeding women, in a world of clinical breastfeeding disruption and conflicting, ineffective clinical responses.

DMER aetiology: hypotheses

Research has shown that milk ejection patterns are highly variable between women and mostly not detected by women. We need investigations using ultrasound imaging to know for sure if the DMER sensations are actually concurrent with ductal dilations.

Hypothesis 1 (NDC)

Could some women have nipple stromal inflammation from repetitive bending and deformational forces during breastfeeding which isn't experienced as direct nociceptive pain during breastfeeding, but as an unpleasant bodily and emotional sensation with letdowns? Could this be because inflammation in the nipple stroma, with its associated elevated interstitial pressure, intensifies when the lactiferous ducts dilate, resulting in a pro-inflammatory neurotransmitter dump (e.g. of cytokines)? Expansion of the ducts, both in the nipple and breast stroma, places positive pressure upon, or compresses, the stroma including the interstitial tissues during letdown.

Would this be exacerbated by nipple and breast tissue drag? Could this be why a majority of women in the Cappenberg et al 2025 study below found the DMER was alleviated or disappeared with pumping - because there was less nipple and breast tissue drag?

I look forward to studies concerning DMER which address the underlying fit and hold problems which so often result in breast tissue drag and repetitive micro-trauma, to investigate the extent to which aversive sensations with letdown, including emotional distress, nause, and churning in the stomach, resolve once mechanical vectors of force are optimally aligned. I would expect multiple factors, including psychological, come into play with DMER but investigation of the role of mechanical forces should be an early investigation. Self-report or even health professional report of 'good attachment and positioning' is not adequate, since so many women and their health professionals believe there is good fit and hold when in fact that woman is experiencing ongoing mechanical microtrauma of her nipple.

Hypotheses 2 and 3

• It has been hypothesised that DMER results from a prolactin spike. However, prolactin leels peak at about 30 minutes after the beginning of a feed, which does not accord with the specific temporal association between DMER and letdowns.

• It has been hypothesised that DMER results from a negative effect of oxytocin. Because the woman will have been exposed to large amounts of systemic oxytocin intrapartum, and also at other times of contact with her baby, without reports of dysphoric responses, it seems unlikely that oxytocin release is the explanatory mechanism.

Recommended resources

Do you have Dysphoric Milk Ejection Reflex?

What does the research say about Dysphoric Milk Ejection Reflex?

Do you have Breastfeeding Aversion Response?

What does the research say about Breastfeeding Aversion Response?

Selected references