Progesterone Should Not Be Routinely Targeted or Monitored in Transgender Women
Progesterone is not recommended in standard gender-affirming hormone therapy for transgender women, and therefore no serum progesterone range should be targeted. The most authoritative guidelines—the 2009 Endocrine Society Clinical Practice Guideline 1 and the 2023 update 2—do not include progesterone as part of standard feminizing hormone therapy and provide no target ranges for progesterone levels.
What the Guidelines Actually Recommend
The established hormone regimen for transgender women consists of:
- Estrogen (oral, transdermal, or parenteral) targeting serum estradiol levels of 100-200 pg/mL 1
- Antiandrogen therapy (spironolactone, cyproterone acetate, or GnRH agonists) targeting testosterone levels <50-55 ng/dL (female range) 1, 2
Progesterone is notably absent from these evidence-based guidelines 1, 2. The 2009 Endocrine Society guideline explicitly describes the MTF regimen as "more complex than the FTM regimen" but only discusses estrogen plus antiandrogen combinations—progesterone is not mentioned as part of standard therapy 1.
The Evidence Gap on Progesterone
Despite progesterone's absence from guidelines, research shows it is commonly used off-label:
- A 2025 survey found that over half of transgender women use progestogens, with oral micronized progesterone (58.4%) being most common 3
- The primary reason cited is hoped-for breast development (85.2% of users) 3
- Most users report satisfaction (71.9%), but also note "barriers and lack of clarity surrounding effectiveness" 3
However, systematic reviews find no conclusive evidence for benefit:
- A 2022 systematic review found no conclusive evidence for improved breast development or quality of life with progesterone use 4
- The same review identified increased thromboembolism risk and decreased HDL with progestogen use 4
- A 2024 narrative review concluded that "the use of progesterone in the transgender woman population is a topic that has yet to be sufficiently researched" 5
Clinical Pitfalls and Caveats
If patients are already using progesterone off-guideline:
- There is no established therapeutic range for serum progesterone in this population
- Monitoring progesterone levels has no evidence-based target and is not clinically useful
- Focus monitoring on estradiol (100-200 pg/mL) and testosterone (<50 ng/dL) instead 1
Safety concerns with progesterone use:
- Reported cases include venous thrombosis (n=6), pulmonary embolism (n=4), and stroke (n=4) in one survey 3
- Decreased HDL and increased thromboembolism risk documented 4
- Common side effects include breast pain (28.7%) and mood fluctuation (21.9%) 3
The Bottom Line
Since progesterone is not part of evidence-based feminizing hormone therapy, no serum progesterone range should be targeted. If patients request progesterone based on anecdotal reports, counsel them that current guidelines do not support its use, evidence for benefit is lacking, and potential harms exist. Direct clinical monitoring toward the established targets: estradiol 100-200 pg/mL and testosterone <50 ng/dL 1, 2.