Search outcome

In total, 3781 academic records were identified. Citations were imported to Endnote and de-duplicated (Fig. 1). In the grey literature search, 526 records were identified (Fig. 1). Citations were inputted manually to an Excel spreadsheet and de-duplicated by hand.

Fig. 1

PRISMA 2020 flow diagram for new systematic reviews which included searches of databases, registers and other sources. *Consider, if feasible to do so, reporting the number of records identified from each database or register searched (rather than the total number across all databases/registers). **If automation tools were used, indicate how many records were excluded by a human and how many were excluded by automation tools. From: Page MJ, McKenzie JE, Bossuyt PM, Boutron I, Hoffmann TC, Mulrow CD, et al. The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. BMJ 2021;372:n71. https://doi.org/10.1136/bmj.n71. For more information, visit: http://www.prisma-statement.org/

Findings

One hundred and sixteen records were identified in the search on academic databases (n = 24 from academic databases, n = 92 from non-academic databases) including two case studies [8, 26], three case reports [9, 19, 21], one case series [10], one letter to an editor [14] and a response to this letter [13)], one commentary [24], one meta-ethnographic review [27], one descriptive study [30], one cross sectional descriptive study [23], one position paper [12], two interpretive phenomenological analyses [12, 29] one qualitative study [25] one mini review [20], one prevalence study [17], one survey [22], one cross sectional survey [28], one integrative literature review [15], one correspondence [16], one retrospective study [11], a mixed-methods study [37] and one perspective piece [18]. Academic records originated from several countries including the United Kingdom (n = 2), Ireland, (n = 1) the United States of America (USA) (n = 7), Australia (n = 7), Japan (n = 1), the Netherlands (n = 1), Egypt (n = 2), China (n = 1) and Turkey (n = 1). One study was developed in collaboration between researchers in the Netherlands and the USA. Sixteen academic records related specifically to D-MER [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23] and seven to BAR [24,25,26,27,28,29,30]. One study focused on maternal experiences of embodied emotional sensations during breastfeeding and included information on both D-MER and BAR [5]. The grey literature consisted of 36 articles, 29 blogs, three news articles, three webpages, four websites, 10 social media posts, two forum posts, two interviews and three books. A total of 41 records related specifically to D-MER and 48 to BAR. Two articles described negative emotional experiences of breastfeeding and milk ejection more generally and one article focused on distressing embodied emotions while breastfeeding. All records were published between 2010 and April 2024. Data extraction tables including details for both academic and grey literature can be found in Appendices 2&3, respectively.

Themes

Five key themes were identified: negative emotional experiences of breastfeeding and milk ejection, suggested causes, coping strategies, potential impacts, and prevalence.

Negative emotional experiences of breastfeeding and milk ejection

The literature described a range of negative emotional experiences and physical sensations associated with breastfeeding and milk ejection.

Onset

A high proportion of records relating to D-MER and BAR described onset as defining features and key indicators of both phenomena (D-MER, n = 67; BAR, n = 55). A rapid onset of dysphoria, just prior to and during milk ejection was identified as a defining characteristic of D-MER in 100% (n = 67) of D-MER related records [8, 9]. Similarly, all BAR records (100%) described how BAR only occurred in relation to breastfeeding (n = 55).

Duration

D-MER experiences were described as brief, lasting between 30 s and 10 min [8, 9] whereas BAR feelings (once started) would persist until the infant de-latched [25, 26].

Emotional response

Records highlighted how manifestations of D-MER and BAR differed. Heise and Weissinger [9] described D-MER feelings as existing on a ‘spectrum’ of sadness, anxiety, or anger, while women experiencing BAR spoke of feelings of revulsion, disgust, and an overwhelming urge for the baby to de-latch [29, 30] (Table 2.).

Table 2 D-MER and BAR experiencesPhysical/visceral sensations

In addition to emotional responses, many women also described physical/visceral responses to D-MER and BAR. For D-MER, these included nipple pain during milk ejection [23, 36], nausea, food revulsion, appetite loss [21] and extreme thirst [37], whereas for BAR, women commonly experienced skin- crawling, tingling, and prickling, throat-tightening and gut-wrenching sensations [24, 25, 29] (Table 2).

Suggested causes

Several causes for BAR and D-MER were proposed. Ovulation and menstruation were suggested as increasing the likelihood of BAR [25, 26], suggesting hormonal shifts may trigger BAR for some, and many women described BAR as more common when breastfeeding while pregnant, breastfeeding toddlers, and when tandem feeding [24,25,26,27]. One participant in the qualitative study by Watkinson, Murray, and Simpson proposed a theory for this [5]:

“It feels like my body is rejecting…the milk theft…from the…[younger]…child … and that’s being expressed by my body like a physical revulsion.” ([5], p.58).

Two hypotheses were suggested as causes for D-MER. The first was the abrupt drop in dopamine which occurs just prior to the milk ejection reflex [8] The second suggested oxytocin released during milk ejection triggered the fight or flight response in some women [12, 13].

Coping strategies

Being aware of and understanding D-MER and BAR as discreet phenomena was crucial for helping women cope with their experiences [8, 9, 24, 26], but in general, knowledge of D-MER and/ or BAR amongst the public and maternal health community was considered low [5, 8, 9, 18,19,20, 22]. Sharing experiences of D-MER with health professionals could lead to misdiagnoses of postnatal depression or anxiety [5, 18, 37]. In contrast, using the internet to share information and access support was considered invaluable [8, 24, 25, 37]. Being believed and having D-MER experiences validated improved women’s ability to cope with D-MER [37], and in general, self-care was reported to alleviate both D-MER [8, 12] and BAR [25,26,27]. Sufficient nutrition, hydration, nutritional supplements and sufficient sleep were associated with complete cessation of BAR feelings for some [25,26,27]. Similarly, sufficient sleep was reported to reduce the frequency of D-MER [8, 12]. Practices such as mindfulness, relaxation and skin- to skin mother-infant contact were reported as helpful in alleviating the intensity of D-MER episodes [12].

Potential impacts

D-MER and BAR impacted women negatively in several ways; both phenomena were described as unexpected, difficult, isolating and frightening, feelings that were often compounded by the limited awareness of either phenomena:

“I was scared … No one seemed to understand … [one]… friend… looked at me like I was crazy” ([26], p.38 -BAR).

In addition to primary experiences of anger during BAR, the nature of episodes led to secondary feelings of guilt and maternal failure for some:

“…aversion is really horrible, it takes away that loving feeling … it makes you want to stop [breastfeeding]… all together…then it makes you feel guilty for feeling like this” ([25], p. 451-BAR).

Women also described feelings of internal conflict with BAR and D-MER, where wanting to stop and wanting to continue breastfeeding co-existed [10, 25, 37].

“I wanted to keep on breastfeeding, but … I… [also]…didn’t want to…it is a…fight inside me every time” ([37], p.13-D-MER).

However, the role of D-MER and BAR in prompting breastfeeding cessation was unclear; while some women stopped breastfeeding sooner than planned because of D-MER or BAR [8,9,10, 14, 19, 28, 37], others were able to continue [11, 24, 37].

Prevalence

Suggested prevalence of D-MER and BAR was described in five records [n = 4 D-MER, 11,17,22,23; n = 1 BAR, 28]. For D-MER, rates varied widely from 6% [17]− 28% [23]. The study focusing on prevalence of BAR found 23% of participants were affected by the phenomena [28].