Lactation and Testosterone: What do we know?

During the postpartum period, many transgender gestational parents find themselves stuck between bodyfeeding their infants or resuming testosterone. They may want to nourish their babies using their own milk, while also wanting to start or resume testosterone. It’s possible to transition to formula or donor milk, of course, but what if you want to do both? One case study looks at this question.

The study, published in September of 2021, looks at one 30-year-old transgender man who wanted to nurse while taking testosterone. To date, no other studies have measure the presence of testosterone in human milk, examining its possible negative impacts on nursing babies. This patient began giving himself shots of testosterone at 13 months postpartum. The researchers began collecting blood from both the father and his baby over the following several months, in addition to collecting milk samples for study.

The transgender father achieved his testosterone level goal within two weeks of beginning his injections and the concentration of testosterone in his milk increased over that same 14-day period. However, the calculated relative infant dose remained under 1% and the toddler had no observable side effects. Blood tests found that the child’s testosterone concentrations remained undetectable throughout the study period.

While this is only one study on one individual, the information can still help transgender parents assess the relative risks and rewards of lactation while on testosterone.

https://journals.sagepub.com/doi/abs/10.1177/08903344211037646