Progesterone During Gender Transition

Progesterone is a naturally occurring female sex hormone produced by the ovaries and placenta during the second half of the menstrual cycle and during pregnancy.

Background

Progesterone is a naturally occurring female sex hormone produced by the ovaries and placenta during the second half of the menstrual cycle and during pregnancy. In transgender healthcare, it is sometimes added to feminizing hormone therapy.

Claims and evidence

Proposed effects include changes in breast development, libido, mood and sleep. The Endocrine Society guideline (2017) and version 8 of the WPATH Standards of Care (2022) note that the scientific evidence for these effects is limited and inconclusive. Prescribing is partly based on patient experience.

Risks and considerations

Progesterone can cause fatigue, mood problems and an increased risk of blood clots. When adding it to estrogen, it is important to discuss the indication and monitoring with the prescribing physician.

Two types of medication

In practice, the name progesterone refers to two groups. Micronized progesterone is identical to the hormone produced naturally by the body. Synthetic variants, known as progestogens, are similar but have different properties. In a large study of postmenopausal women, the combination of estrogen and a synthetic progestogen was associated with more breast cancer and more cardiovascular disease. It is not known whether this also applies to micronized progesterone and transgender women. Cyproterone acetate, which is widely used in the Netherlands to suppress testosterone, also acts as a progestogen.

Research underway

The idea that progesterone makes breasts fuller and rounder is based on the hormone's role in breast development in girls and on users' experiences. Until recently, this had never been investigated in a comparative study. Researchers in Amsterdam have therefore begun a randomized study into the effect of adding progesterone on breast development. Until the results have been published and confirmed, prescribing remains a decision to be weighed by the physician and patient.

Self-medication

Progesterone is often recommended on internet forums and can be purchased without a prescription from foreign online stores. Use without medical supervision is not recommended: the dosage and quality are uncertain, and blood levels and side effects are not monitored. See estrogen, breast augmentation, risk of blood clots with estrogen and side effects of hormones.