A step closer for trans women Oleksiy Maksymenko/Getty

A 30-year-old transgender woman has become the first officially recorded to breastfeed her baby. An experimental three-and-a-half-month treatment regimen, which included hormones, a nausea drug and breast stimulation, enabled the woman to produce 227 grams of milk a day.

“This is a very big deal,” says Joshua Safer of Boston Medical Center, who was not involved with the treatment. “Many transgender women are looking to have as many of the experiences of non-transgender women as they can, so I can see this will be extremely popular.”

The transgender woman had been receiving feminising hormonal treatments for several years before she started the lactation treatment. These included spironolactone, which is thought to block the effects of testosterone, and progesterone and a type of oestrogen.

This regimen enabled her to develop breasts that looked fully grown, according to a medical scale that assesses breast development based on appearance. She had not had any breast augmentation surgery.

When her partner was five-and-a-half-months pregnant, the woman sought medical treatment from Tamar Reisman and Zil Goldstein at Mount Sinai’s Center for Transgender Medicine and Surgery in New York City. Her partner had no interest in breastfeeding, she explained, so she would like to take on that role instead.

Enough for six weeks

A hormone called prolactin usually stimulates the production of breastmilk in women who have just given birth, but this chemical isn’t available as a lab-made drug. Instead, the woman decided to try using a nausea drug called domperidone to trigger breastmilk.

There’s anecdotal evidence that this drug may boost milk production, although the US Food and Drug Administration has previously warned that it shouldn’t be used for this purpose.

She took it with increasing doses of the hormones oestrogen, progesterone and spironolactone. At the same time, she began to use a breast pump to stimulate her breasts.

Within a month, the woman was able to express milk droplets. After three months of treatment, this increased to 227 grams of breast milk per day. Once the baby was born, she was able to exclusively breastfeed the infant for six weeks – during which time a paediatrician confirmed the baby was growing and developing normally and healthily.

Although significant, this is below the average of around 500 grams that a baby consumes by the time the it is 5 days old. After six weeks, the woman supplemented her breastfeeding with formula.

Unknown effects

This is the first case of breastfeeding by a trans woman to be reported in the medical literature, say Reisman and Goldstein. Safer agrees. “It’s out there on internet forums, but there’s a lot on the internet that’s true or untrue to varying degrees,” he says. “It’s a very big deal to have this recorded in a reliable document.”

But Safer isn’t surprised that it’s possible. “When I treat transgender women, we see good breast development” he says. There’s no reason why the cells in these breasts wouldn’t make milk the same way that those of non-transgender women do, he says, although he notes that it is unclear to what extent the drugs and hormones helped. “For all we know, breast stimulation alone might be sufficient.”

If the treatment is proven safe and effective, it could benefit the babies of other transgender women, as well as women who adopt or those who have difficulty breastfeeding, says Safer.

However, the woman’s breastmilk has not been assessed yet, so we don’t know if it has the same mix of components as in milk from new gestational mothers. This means the practice cannot yet be recommended, says Madeline Deutsch at the University of California, San Francisco. She says she can see the potential benefits of breastfeeding, but that the long-term impact of this milk on the baby – including on subtle measures like IQ – is unknown.

Deutsch herself is a transgender woman with a six-month-old baby who is currently being breastfed by Deutsch’s wife, who was the gestational mother. “I am very sad not to be able to breastfeed her and at the same time I did not consider doing this for the above reasons,” she says.

Nevertheless, Safer thinks there is likely to be demand for treatments like this. “This is very special,” he says. “It will be very important for the many transgender women who want to breastfeed but do not feel they have the opportunity to do so.”

Journal reference: Transgender Health, DOI: 10.1089/trgh.2017.0044

Read more: Why overzealous breastfeeding advice can be bad for babies