Background: Dysphoric milk ejection reflex (D-MER) is a phenomenon that occurs before milk letdown and is described as a wave of negative or devastating emotions, ranging from mild to severe and lasting for seconds to minutes. To date, there has been little research regarding this phenomenon. This study aims to determine the prevalence of D-MER in our population as well as its association with postnatal depression scores and breastfeeding self-efficacy. Methods: Lactating persons between 4 and 12 weeks postpartum at our institution were invited to complete an anonymous 59-question survey via an online platform. Questions asked included patient demographics, presence of symptoms of dysphoria (including timing, duration, and frequency), the Edinburgh Postnatal Depression Scale (EPDS), and the Breastfeeding Self-Efficacy Scale Short Form (BSES-sf). Results: In total, 201 women completed the survey. Twelve women were classified as likely having D-MER (6%). Symptom resolution primarily occurred within a minute to 5 minutes (58%). Mean EPDS scores differed significantly between those with likely D-MER and those without (12.2 vs. 5.4, p = 0.002). BSES-sf scores differed significantly between the two groups (43.1 vs. 52.5, p = 0.009). Preexisting depression or anxiety was not associated with D-MER (p = 0.133), other reported mood disorders differed significantly between those with D-MER and those without (p = 0.004). Demographic characteristics of women with and without D-MER were similar. Conclusion: D-MER prevalence may be lower than previously reported. Patients with likely D-MER appear to have lower breastfeeding self-efficacy and higher depression scores. Those with preexisting mood disorders may be at higher risk of experiencing D-MER.

Introduction: Dysphoric milk ejection reflex (D-MER) is emerging as a recognized phenomenon to describe an abrupt dysphoria, or undesirable feeling that occurs with the milk ejection reflex (MER) and then goes away after a few minutes. The purpose of this study was to determine the prevalence of D-MER among breastfeeding women and to describe the experience of symptoms associated with D-MER. Materials and Methods: To determine the prevalence of D-MER, a retrospective chart review was conducted over a 12-month period on women presenting for their 6- to 8-week postpartum visit. To describe the experience of D-MER, an anonymous cross-sectional survey consisting of 36 items was made accessible through a link to an online survey management platform. Participants were recruited through both paper and electronic posters at a variety of venues. Results: A prevalence rate of 9.1% was found. The respondents described similarities in their experiences with D-MER, to include feelings coming on suddenly and lasting for <5 minutes. The respondents described feeling anxious, sad, irritable, panicky, agitated, oversensitive, and tearful most often. Conclusion: This is the first study to quantify a prevalence rate and describe suspected experiences of D-MER. It provides the groundwork for future research to explore other contributing factors or relationships that may be relevant to D-MER. The findings support that the experience of D-MER is different from that of postpartum depression. Future research exploring the behavior of hormones and neurotransmitters within the context of lactation could contribute to the knowledge regarding D-MER.

Dysphoric milk ejection reflex (D-MER) is characterized by an abrupt dysphoria, or undesirable feeling that occurs with the MER and continues for no more than a few minutes. After milk ejection, the dysphoria vanishes.
This case series provides a report of three women who have experienced D-MER. All three women described the sudden onset of negative feelings at the initiation of each breastfeeding session. The dysphoria vanished after each milk ejection.
Literature on D-MER is limited to one published qualitative research study and two published case reports. As a result, lactation professionals and other providers in the healthcare setting rarely recognize this condition.
The case studies presented here provide evidence for the presence of D-MER. Research is needed to better understand its pathophysiology, incidence, and treatment options.

In addition to its peripheral actions, oxytocin released within the brain is important for birth and essential for milk ejection. The oxytocinase enzyme (placental leucine aminopeptidase; P-LAP) is expressed both peripherally and centrally. P-LAP controls oxytocin degradation in the uterus, placenta and plasma during pregnancy, although its role in the hypothalamus is unclear. We investigated P-LAP expression and activity in the hypothalamus in virgin, pregnant and lactating rats, as well as its role in vivo during the milk-ejection reflex. P-LAP mRNA and protein were expressed in magnocellular neurones of the supraoptic (SON) and paraventricular (PVN) nuclei. Oxytocin neurones co-expressed P-LAP without strong subcellular co-localisation of oxytocin and P-LAP, indicating that they are packaged in separate vesicles. Examination of the intracellular distribution of oxytocin and P-LAP showed a redistribution of P-LAP to within 1 μm of the plasma membrane in the somata of oxytocin neurones during lactation. Both P-LAP mRNA expression and hypothalamic leucyl/cystinyl aminopeptidase activity in the soluble fraction were higher during lactation than in late pregnant or virgin states. Inhibition of central enzyme activity by i.c.v. injection of amastatin in anaesthetised suckling mothers increased the frequency of reflex milk ejections. Because hypothalamic P-LAP expression and activity increase in lactation, and the prevention of its action mimics central oxytocin administration, we conclude that P-LAP regulates auto-excitatory oxytocin actions during the suckling-induced milk-ejection reflex.