Lactation is Not Only For Cisgender Biological Mothers
Classic observations of nonconventional lactation and new findings offer hope for all parents
Lactation is most commonly associated with a mother who has just given birth. But, it’s 2022 and the narrative around who can lactate has expanded. First, a fun fact: in the 1990’s, researchers found that some male fruit bats naturally lactate as they have functional mammary glands that produce small amounts of milk . Because male humans do indeed have mammary glands, albeit typically inactive, male lactation is physiologically possible if a myriad of factors align, including hormonal cues that give the greenlight to produce milk. But, since male humans a) are not male fruit bats, and b) don’t experience the hormonal changes during pregnancy that prepare the body for a baby’s arrival, external interventions are necessary to induce lactation. But, in 2010, a man did lactate naturally because he had a pituitary tumor that increased his prolactin level to 13,050 pmol/L (normal: 109–522)and decreased his testosterone level to 6.4 nmol/L (normal: 10.4–31.0) . Among other factors, hormones are key players in lactation.
Source: 2014 Article by Pamela K. Murphy, PhD, MS, APRN-BC, CNM, IBCLC, Director of Education, Research & Professional Development, Ameda, Inc. Graphic adapted from Love SM, Lindsey K. Dr. Susan Love’s Breast Book. 1st ed. MA: Addison-Wesley; 1990. 
Lactation, either spontaneous or induced, has been demonstrated not only in cisgender females who have given birth, but also in non-birthing parents including transgender women. Today, non-birthing cisgender women who become parents by way of adoption, surrogacy or other means can seek hormone treatments that may enable them to begin and continue lactating [1,2]. A recent peer-reviewed study  of induced lactation opens new possibilities for transwomen, offering the potential for inclusion into experiencing a previously biologically female-only experience and offering their babies the benefits of breastmilk.
Rachel Wamboldt, Shirley Shuster, and Bikrampal S. Sidhu, three clinical researchers at the Kingston Health Sciences Center at Queenʼs University in Kingston, Ontario, Canada were presented with a challenging case — their study was published in early 2021 . A transwoman whose female partner had been breastfeeding their infant requested treatment to enable her to lactate so her partner could return to work. She first tried to induce lactation by attaching a pump to her breasts for 5 minutes, 3–4 times per day. This method only yielded a few drops of milk a day. After just over one month of hormone therapy, she produced 3–5oz of milk which supplemented the solid foods their 11-month old was also consuming. This is only the second case in the medical literature to demonstrate successful breastfeeding in a trans woman through use of hormonal augmentation .
The researchers used the Newman-Goldfarb protocol , which uses domperidone, an anti-nausea drug that is not FDA approved for this purpose , in addition to progesterone, to induce lactation in non-gestational cisgender and transgender women. The hormone treatment triggers prolactin release which, along with progesterone, first tells mammary glands to develop in preparation for lactation, then gives mammary epithelial cells the green light to produce milk. The authors share that “since development of breast tissue is similar between human males and females until the hormonal influences that occur at puberty, it is not unreasonable that under the right hormonal regulation, including the ongoing suppression of androgen, that trans women could lactate” (pg. 3).
The hormones the woman took during her MTF transition may have also contributed to preparing her body for induction of lactation. After starting the Newman-Goldfarb protocol, she also continued physical stimulation of her breasts with an electric pump. She was able to produce 3–5oz of milk daily for approximately 6 months. While this volume of milk isn’t enough to sustain an infant, her son was already consuming solids so he wasn’t solely relying on breastmilk for nutrition.
In a separate study from 2018 that used a similar protocol, an adoptive mother of premature twins began a controlled regimen of treatment several months prior to adoption, and at two months of age both infants were exclusively receiving human milk produced by their adoptive mother .
The impact of hormones on lactation in ciswomen is significantly different from the effects of hormones administered to induce lactation in transwomen and non-birthing parents [1,7]. Specifically, the “induction of lactation in transwomen may require ongoing androgen suppression”  to block the production of male sex hormones. The medications used for induction may have side effects (though none are currently known) and associated risks (e.g., safety concerns with IV use) that an untreated birth mother would not encounter . Furthermore, the relatively low milk supply  is an ongoing barrier to exclusive breastfeeding in transwomen.
These discoveries are exciting as they expand the availability of breastmilk to babies of diverse families and expand the field’s understanding of hormones in lactation, but the studies do have limitations. First, the two successful studies with transwomen each had a sample size of one which isn’t enough to draw definitive conclusions about this approach. Second, the nervous, immune, and endocrine systems interact in highly complex ways  that can affect lactation and are yet to be thoroughly understood.
Although research in this field is now in a very early stage, it opens new avenues for inquiry and exploration and recognizes the desire for breastfeeding — or chestfeeding, a relatively recent and more inclusive term — among non-traditional parents. Likewise, BIOMILQ recognizes the importance of offering the nutrition of human milk to all parents, regardless of biology. So, if parents decide that initiating lactation isn’t the right path for them once there is a more established clinical treatment, cell-cultured human milk may provide what they’re looking for.
1. Wamboldt R, Shuster S, Sidhu BS. Lactation induction in a transgender woman wanting to breastfeed: Case report. J. Clin Endocrinol & Metab. 2021;20(20):1–6. doi:10.1210/clinem/dgaa976
2. Palmquist A. Cooperative lactation and the mother-infant nexus. Pages 125–142 in Gowland R, Halcrow S eds., The Mother-Infant Nexus in Anthropology. Springer, Cham, Switzerland; 2020.
3. Francis CM, Anthony ELP, Brunton JA, Kunz TH. Lactation in male fruit bats. Nature. 1994; 367:691–691.
4. Szucs KA, Axline SE, Rosenman MB. Induced lactation and exclusive breast milk feeding of adopted premature twins. J Hum Lact. 2010;26(3):309–313. doi: 10.1177/089033441037110.
5. Newman J, Pitman T. Dr. Jack Newmanʼs Guide to Breastfeeding. Revised ed. London, UK: Pinter & Martin; 2015.
6. Martin P. The healing mind. NY: St. Martinʼs Griffin; 1997.
7. Reisman T, Goldstein Z. Case report: Induced lactation in a transgender woman. Transgender Health. 2018; 3.1:24–26. doi:10.1098/trgh.2017.0044.
8. US FDA. How to Request Domperidone for Expanded Access Use. 2021. https://www.fda.gov/drugs/investigational-new-drug-ind-application/how-request-domperidone-expanded-access-use.
9. Anoop, T. M., Jabbar, P. K., & Pappachan, J. M. (2010). Lactation associated with a pituitary tumour in a man. CMAJ : Canadian Medical Association journal = journal de l’Association medicale canadienne, 182(6), 591. https://doi.org/10.1503/cmaj.090888
10. Murphy, Pamela K. (2014) “How your breasts make milk.” Ameda. https://www.ameda.com/media/education/HowDoMyBreastMakeMilk_26401173_Eng_2.21.pdf