It was 2017. I was 40, and I’d just had my son, my first and only child. It was overwhelming: the extravagant newness of becoming a parent, meeting my kid, the travesty that is American postpartum care. But there was something else I couldn’t identify. Multiple times a day, I was hit with a sudden and intense wave of sadness. I lost the ability to speak and to think clearly. If I was eating, I lost my appetite; if I wasn’t, I felt nauseous. All I could do was stop, close my eyes and wait for the feeling to pass, which it always did after a minute or two. After three months, I started putting the pieces together: immediately after those intense waves of sadness, my breasts would get full and tingly – meaning my milk was letting down – my body’s way of telling me it was time to feed my son. One despairing afternoon, I Googled: “Why am I sad when I breastfeed?” I knew I didn’t have postpartum depression – PPD was an ongoing condition, whereas these spikes of feeling came suddenly and, just as quickly, went away. Within minutes, I’d learned that I wasn’t crazy and what I was experiencing had a name: D-MER. What is D-MER? Dysphoric milk ejection reflex, or “D-MER” – pronounced by saying all the letters rather than, for example, “deemer” – is “an anomaly of the milk ejection reflex that results in a brief but intense negative emotional response in the breastfeeding mother that lasts for usually 30 to 90 seconds”, says Alia Macrina Heise, a retired international board certified lactation consultant (IBCLC) who coined the term around 2008. What causes D-MER? Macrina Heise, who experienced D-MER with her third child, says it’s probably caused by “inappropriate dopamine activity” right before a person’s milk lets down. Two main hormones are involved in the lactation process, she explains: oxytocin and prolactin. Oxytocin – known for warm, fuzzy feelings – is what gets breast milk from the back of the breast out the nipple. At the same time that milk is moving out, the brain gets the message that more needs to be made – that’s what prolactin does. But prolactin and dopamine – also a hormone, and a neurotransmitter – have an inverse relationship in the body, meaning that if one goes up, the other must go down. The prevailing theory is that, with people who experience D-MER, dopamine drops a little too far or too fast when prolactin levels go up – but “after dopamine restabilizes in the body … the mom feels fine again”, said Macrina Heise. What does D-MER feel like? Every person with D-MER experiences a similar rush of intense emotion, Macrina Heise says, but the actual “emotional experience is different for each mom”. Macrina Heise says she experienced “random and brief moments where I felt like I was doing everything wrong. I was the problem. Life was not safe. I was not a good person.” But that was the dopamine drop talking – not long afterward, the bad feelings went away. Others might say they experience dread, anxiety, homesickness, “a pang” or suicidal ideation. “It’s all across the board, and some of that is severity, and some of that is emotion concepts,” she says, referring to how different people assign different words or concepts to bodily sensations. Who experiences D-MER? “There’s no common denominator” for who experiences D-MER, says Macrina Heise. Anyone who is lactating can experience it, regardless of age, ethnicity, socioeconomic status or any other demographic factor. A person can experience it with any birth, Macrina Heise adds, although someone who experiences it with one birth is “overwhelmingly” likely to experience it with subsequent births. Is D-MER rare? D-MER is often described as rare, but Macrina Heise says she doesn’t agree with that designation; as a 2023 study states: “It is only recently gaining recognition in the academic literature.” Other studies have estimated that between 3% and 13% of lactating people experience it. As is typical with women’s issues, there needs to be more research. Samantha Shaw-Johnston, a perinatal and reproductive psychiatrist at the University of Michigan, says she’s only worked with two or three patients with D-MER in the last five years. But this isn’t necessarily an accurate reflection of the condition’s prevalence. “​It’s still unclear what proportion of breastfeeding individuals do experience this, because so many people don’t even know about it,” she says. “I think ‘rare’ is used because we’re still trying to soften it and not make it look like this horrible thing that could happen to you if you decide to breastfeed your baby,” Macrina Heise said. She believes that although more lactation consultants know about D-MER, they may not be proactive about sharing information due to “the very well-intended, but very misplaced mission of ‘breast is best’”. Macrina Heise recalled an essay by Anna O’Neil that noted the first D-MER prevalence study showing a rate of 9.1%, whereas the prevalence rate for mastitis is generally 10%: “She said, every mother who starts breastfeeding knows what mastitis is, that she’s at risk for it, and what the warning signs are. How come this thing [D-MER] … doesn’t have the same awareness?” How do you treat D-MER? “Education is the most important thing” in responding to D-MER, says Macrina Heise. The route to education is sadly similar for many people: lactating person has recurring, awful feeling; figures out it seems to be connected to nursing; Googles; finds Macrina Heise’s Facebook support group. Others may never realize they have, or have had, D-MER. Post after post from the Facebook group confirms that knowing the experience is real – and that the wave of bad feelings will always go away in seconds – makes nursing people feel less bad and less alone. It also allows people to make an informed decision about whether to hang in with breastfeeding or whether to stop. One promising treatment suggested by members of the Facebook group is simply to drink a glass of cold water – a recommendation Macrina Heise has found corroboration for in sports medicine research studies. Athletes are interested in prolactin because lower levels of the hormone may mean lower fatigue. Cooling of the head, neck or face has been shown to lower prolactin levels during exercise, which – good for those with D-MER – raises dopamine because of that inverse relationship. Other anecdotal remedies include taking a B vitamin complex, vitamin D or magnesium, although these have not been studied. The most important aid is awareness, says Macrina Heise. “We all have emotions that are real, but not true,” she says, “and how we then approach those emotions … is really important, because it chooses our response to it. Never is that anywhere more true than a mother with D-MER – because she does not need to wonder if she is in the wrong marriage. She does not need to wonder if she’s a good mother or a bad mother.” Education is key, agrees Shaw-Johnston, as is understanding more about how our sympathetic nervous system fuels negative or intense emotions. “As soon as you become aware that it’s a biological process that’s happening and it’s not an individual failing, that helps decrease some of the distress around the experience,” she said. Knowing it’s a temporary and physical phenomenon gives people the context they need to deal with it, agrees Macrina Heise: “‘This hurts, this feels like shit, but it’s gonna go away – and it means nothing.’” Can healthcare providers help? Although 15% of pregnant people in the US get inadequate prenatal care, and an increasing number get none at all, a patient’s point of contact tends to be their OB-GYN. Shaw-Johnston says this is an opportunity for doctors to share information. Her hospital, for example, gives pregnant people “a whole spiral-bound book” with information on everything from pregnancy symptoms to newborn care. Colleagues have discussed adding a mental health component that could address issues such as D-MER: “Just knowing about [perinatal mental health experiences] and knowing that they’re not something to be ashamed of … is extremely powerful.” Jenny Pritchett, AKA Jenny True, is a copy editor at the Guardian US and the author of You Look Tired: An Excruciatingly Honest Guide to New Parenthood