A transgender woman has become the first to be able to breastfeed thanks to hormone therapy.

The woman, who has not been named, fed her baby for six weeks after birth. Incredibly, she was able to lactate without undergoing any surgical procedures, thanks to the help of nurse practitioner Tamar Reisman and programme manager Zil Goldstein from New York's Mount Sinai Centre for Transgender Medicine and Surgery. The patient had been transitioning with hormones since 2011 but had not undergone any feminising surgery such as vaginoplasty or breast augmentation. She approached Reisman and Goldstein as her partner was due to give birth but did not want to breastfeed, according to a case report in the journal Transgender Health. She was prescribed a drug called domperidone, which she took three times daily. It had to be obtained from Canada, as the US Food and Drug Administration banned it in 2004 due to side effects including headache, dizziness, irritability and cramps. This, combined with her dosage of hormones estradiol and micronised progesterone and her use of a breast pump, enabled her to lactate. The baby's paediatrician said that the infant thrived on the breast milk. Both Reisman and Goldstein concluded that more research is needed to determine how to induce lactation without the use of a banned drug. "Future investigation will be required to determine the optimal treatment regimen for induced lactation in transgender women."