Key Timestamps:
- 00:00 - Introduction — Dr. Felice Gersh, 45 years in practice, and why this conversation matters now
- 02:30 - How menopause is finally being recognized as a metabolic shift, not just a reproductive one
- 04:00 - Why hormone dispensaries that skip individual assessment concern Dr. Gersh
- 05:30 - The house fire analogy: why the approach differs for recently menopausal vs. 10+ years post-menopause
- 08:00 - Dr. Gersh’s evolved thinking on progesterone: the shift from “necessary evil” to essential hormone
- 11:00 - What progesterone actually does: receptors in the neurological, cardiovascular, immune, and musculoskeletal systems
- 14:30 - Cyclic hormones and the 28-day lunar rhythm: why continuous dosing does not replicate nature
- 17:30 - The neuroprotective effects of progesterone: Dr. Cabeca’s early clinical observations
- 20:00 - Progesterone and breast health: p53 enzyme, Th2 immunity, and what the research actually shows
- 23:00 - The progesterone vs. progestin distinction: why mixing up these words causes real harm
- 26:00 - Oral progesterone and allopregnanolone: the GABA receptor connection and what 100mg actually does
- 31:30 - Why women may feel “drugged” on nightly oral progesterone — and what the rat data says
- 36:00 - Vaginal and rectal delivery: dosing, endometrial protection, and what the fertility clinic data tells us
- 40:00 - Transdermal progesterone: does it absorb through the skin? Dr. Gersh’s honest answer
- 43:30 - Should postmenopausal women bleed? The case for cyclic withdrawal bleeds and what to watch for
- 47:00 - Cervical cancer’s second peak at age 65 and why pap smears should continue to 75
- 50:00 - Breast cancer and hormones: inflammation, aromatase, estrone vs. estradiol, and informed consent
- 56:30 - The one study that gave breast cancer survivors bioidentical hormones alongside an aromatase inhibitor
- 60:00 - Where to find Dr. Gersh and her practice in Irvine, California
Bioidentical Progesterone for Menopause: What Your Doctor Isn’t Telling You
From The Girlfriend Doctor Podcast — with Dr. Felice Gersh, OB-GYN and Integrative Medicine Physician, 45 years in practice
Your doctor may have told you that if you don’t have a uterus, you don’t need progesterone.
That thinking is forty years out of date.
In this conversation, Dr. Anna Cabeca sits down with Dr. Felice Gersh — a practicing OB-GYN with 45 years of clinical experience, boarded in integrative medicine, and one of the most respected voices in women’s hormonal health — to break down everything the mainstream conversation on progesterone is still getting wrong.
What you’ll find here: why progesterone matters to every organ system in your body, why the way most women take it may not be serving them, the evidence on cyclic versus continuous dosing, and what to do if you’re post-menopausal and wondering whether to bleed or not.
Medical note: This content is educational. Any hormone therapy decisions should be made with your personal physician. If you experience any postmenopausal bleeding, a pelvic ultrasound and GYN evaluation are required regardless of hormone status.
Table of Contents
→ The Problem With How Medicine Thinks About Progesterone
→ What Progesterone Actually Does in the Body
→ Why Cyclic Progesterone Matters More Than You Think
→ Oral Progesterone, Allopregnanolone, and the GABA Receptor: The Nuance Nobody Talks About
→ Vaginal, Rectal, Transdermal: Which Delivery Route and Why
→ Should You Bleed After Menopause? The Honest Answer
→ Starting Hormones After a Long Gap
→ Progesterone After Breast Cancer: Informed Consent, Not Avoidance
→ FAQ: Bioidentical Progesterone in Menopause
The Problem With How Medicine Thinks About Progesterone
Here is the consensus view that most OB-GYNs were trained on: progesterone has two jobs. Help create a pregnancy. Prevent uterine cancer in women on estrogen therapy.
That’s it.
If you don’t have a uterus, you don’t need progesterone. If you’re not pregnant, progesterone is essentially an afterthought.
Both Dr. Gersh and Dr. Anna Cabeca believe this framing is fundamentally incomplete — and potentially harmful to women who deserve better.
“Most doctors only think of progesterone as affecting uterine cancer risk. That’s it. The fact that it has receptors in the immune system, the neurological system, the cardiovascular system, the musculoskeletal system — that’s completely unrecognized, even by experienced OB-GYNs.”
What Progesterone Actually Does in the Body
Progesterone receptors are distributed throughout virtually every organ system. When progesterone declines — and it declines by approximately 75% between age 35 and menopause, compared to 35% for estrogen — the effects are not limited to the uterus.
What progesterone does that most women (and most doctors) do not know:
Neuroprotective: maintains myelin, the insulating sheath around nerve fibers; directly supports brain function and cognitive health
Anti-inflammatory: modulates immune function and reduces systemic inflammation
Mitochondrial support: helps support cellular energy production
Cardiovascular: receptors in heart and vascular tissue
Musculoskeletal: receptors in bone and muscle
Breast health: down-regulates the estrogen alpha receptor, which is the growth-promoting receptor implicated in breast cancer
Mood and sleep: supports the conversion to allopregnanolone, which binds to GABA receptors in the brain (more on this below — it’s more complex than it sounds)
Postpartum mental health: the sharp drop in progesterone after delivery is now understood to be a central driver of postpartum depression
Dr. Cabeca notes that early in her career, she observed women without a uterus who were started on progesterone cream (combined with pregnenolone) consistently report the same things: brain fog lifting, clearer thinking, better sleep, feeling like themselves again. These are neurological effects, not uterine ones.
Why Cyclic Progesterone Matters More Than You Think
The body does not produce hormones at a flat, continuous rate. It never has. Progesterone is produced for approximately two weeks per cycle during the luteal phase, then drops. That rise and fall is not a design flaw. It is the design.
Dr. Gersh makes a foundational argument: the healthiest years of a woman’s hormonal life are her early twenties, when she has cyclic hormones at optimal levels. The goal of hormone therapy should be to approximate that rhythm — not to replace it with a flat, continuous daily dose that no natural physiology has ever produced.
“I’m not smarter than nature. The biggest failed experiment in history is ultra-processed food — we thought we could make food that tastes better and lasts longer. We can’t create hormone regimens that never exist in nature and expect better outcomes than what nature gave us.”
The key clinical point: most of the hormone studies that showed favorable outcomes used cyclic progesterone — two weeks on, two weeks off. That detail is frequently overlooked when the results are summarized.
There is also emerging preclinical data (in rats, which Dr. Gersh is transparent about) suggesting that cyclic estradiol and progesterone produces better cognitive outcomes than continuous dosing. Human trials are needed and do not yet exist at scale.
Dr. Cabeca’s clinical approach: she typically cycles progesterone with three to five days off per month in postmenopausal women, rather than the longer ten to fourteen day cycles Dr. Gersh uses. Both physicians agree on the principle; the exact protocol is individualized.
Oral Progesterone, Allopregnanolone, and the GABA Receptor: The Nuance Nobody Talks About
This is the most technically detailed section of the conversation, and one of the most clinically important.
When progesterone is taken orally, approximately 80–90% of it is metabolized in the liver before it reaches the circulation. What you are left with is not primarily progesterone — it is metabolites, primarily a compound called allopregnanolone.
Allopregnanolone binds to the GABA-A receptor in the brain. In the right amounts, it is genuinely beneficial: calming, sleep-supporting, neuroprotective, and possibly protective against Alzheimer’s disease. The synthetic version of allopregnanolone is now used as an FDA-approved treatment for postpartum depression.
But here is the nuance:
A 100mg oral progesterone dose produces approximately 2.5x the maximum amount of allopregnanolone that a woman would ever naturally have circulating in her blood during a normal luteal phase
A 200mg dose produces approximately 5x the natural maximum
Allopregnanolone at supraphysiologic levels is classified as a controlled substance (same scheduling as Valium and Xanax) due to its sedating, GABA-activating mechanism
Rat studies show that chronic exposure to high allopregnanolone levels causes cognitive impairment
Many women describe feeling “drugged” on oral progesterone — they are, in effect, taking a nightly tranquilizer
When women stop oral progesterone, many report that a fog has lifted — which may mean the sedation was masking, not improving, cognitive function
Dr. Gersh’s clinical position: she is not saying oral progesterone is always wrong. She is saying that nightly oral progesterone, taken continuously, delivers allopregnanolone at doses that exceed natural physiology and that we do not have long-term human data on whether this is safe for brain health. The preclinical signals are worth taking seriously.
For women who say they love oral progesterone at night because it helps them sleep: that may be true. But the mechanism is pharmacologic sedation, not physiologic sleep support. That is a meaningful distinction.
If you are currently on oral progesterone and it is working for you, do not stop without talking to your physician. This section is not a directive — it is context for a conversation you may want to have.
Vaginal, Rectal, Transdermal: Which Delivery Route and Why
If the goal is to get physiologic blood levels of actual progesterone (not allopregnanolone), non-oral routes are worth understanding.
Vaginal
Vaginal delivery produces measurable blood levels of progesterone, bypasses most first-pass liver metabolism, and has strong published evidence for endometrial protection. Women with a uterus get the added benefit of uterine first-pass concentration, which helps achieve complete secretory conversion of the uterine lining.
Dr. Gersh’s current approach: 200–400mg progesterone vaginally or rectally for postmenopausal women. She measures blood levels and monitors the uterine lining with ultrasound as needed.
Note: some of the progesterone tablets sold for oral use (Prometrium) can be used vaginally. In Mexico and parts of Europe, packaging explicitly states both routes. Published research supports this use.
Rectal
Surprisingly effective absorption with no vaginal drainage (the vagina has no sphincter; any suppository placed vaginally will have some leakage). Rectal delivery also bypasses first-pass liver metabolism and produces good blood levels. Dr. Gersh describes it as “mouth opposite” to help patients get past the unfamiliarity.
Transdermal (through the skin)
Progesterone does absorb through the skin. Dr. Cabeca has used progesterone cream (including her own Balance cream, which combines progesterone and pregnenolone) in clinical practice for years with measurable results. The limitation is that transdermal delivery does not always show up reliably in serum blood tests, though it does appear in salivary and urinary measurements.
For women with a uterus who are relying on transdermal progesterone for endometrial protection, Dr. Gersh recommends additional monitoring because the published endometrial protection data for transdermal is thinner than for vaginal or rectal.
Dr. Gersh’s core principle on all routes: measure. Because the body was not designed to receive hormones through any of these routes — it was designed to receive them from the ovary directly into the bloodstream — individual variation in absorption is real. You cannot assume a dose is working. You measure.
Should You Bleed After Menopause?
This is one of the most loaded questions in this conversation — and one of the most misunderstood.
If you give cyclic hormones to a postmenopausal woman with a uterus, timed bleeding is expected. The progesterone causes the uterine lining to undergo secretory conversion. When the progesterone is stopped, the lining sheds. That is not dangerous. That is the designed outcome of cyclic therapy.
The critical distinction:
Timed, expected bleeding after cyclic progesterone = appropriate withdrawal bleed. Not a sign of uterine cancer.
Unexpected, untimed bleeding = always requires workup regardless of hormone status
Any postmenopausal bleeding requires: pelvic ultrasound, GYN evaluation, pap smear
“Bleeding does not mean cancer. It means you’re shedding the lining. But any postmenopausal bleeding needs to be worked up. I don’t care how old you are. You need a pelvic ultrasound and a GYN evaluation. Full stop.”
Both physicians also note: cervical cancer has a secondary incidence peak in the mid-60s that most physicians are not aware of. Dr. Gersh recommends continuing pap smears through age 75.
On the question of whether postmenopausal women should accept having periods: Dr. Gersh believes that if a woman has a uterus and chooses cyclic hormone therapy at physiologic doses, she will likely have withdrawal bleeds, and that this is a sign the therapy is working as intended. Whether a woman chooses this is entirely individual, but the choice should be informed — not decided for her by a physician who finds the conversation inconvenient.
Starting Hormones After a Long Gap
The question of when to start hormones — and how — depends heavily on how long a woman has been without them.
Dr. Gersh uses the analogy of a house fire: if you had a small fire on the stove, you clean up and move back in. If half the house burned down, you cannot just walk back in. The longer a woman has been without hormones, the more likely she has accumulated organ-level damage from their absence.
Her approach for women who have been postmenopausal for a decade or more: start slower, work on reducing systemic inflammation and gut microbiome dysfunction first, then gradually introduce hormones as the receptors come back online.
For women who are recently menopausal (within one to two years): she starts at the optimal dose directly, because the receptor landscape has not had time to significantly degrade.
Both physicians agree: the personalization here is everything. Two women can walk in with identical histories and need very different starting points.
Progesterone After Breast Cancer: Informed Consent, Not Avoidance
This is where both physicians bring nuance that challenges the standard oncology position.
The standard framing: hormones feed breast cancer. Do not give hormones to anyone who has had breast cancer.
The more complete picture from this conversation:
The biggest driver of breast cancer recurrence is inflammation — not bioidentical hormones
Inflammation activates the enzyme aromatase, which converts adrenal androgens into estrone (not estradiol). It is estrone, produced locally in inflamed tissue, that activates breast cancer receptors
Estradiol and bioidentical progesterone are both anti-inflammatory
Progesterone down-regulates the estrogen alpha receptor — the growth-promoting receptor in breast cancer
At least 12 studies now show that estradiol does not increase breast cancer risk and may reduce it
One study gave women post-breast-cancer bioidentical hormones alongside an aromatase inhibitor to block locally produced estrone — outcomes were favorable
For women with a prior breast cancer diagnosis who want to discuss hormones:
Women not in active treatment and without known metastatic disease may choose hormones with full informed consent
Ductal carcinoma in situ (DCIS) is not technically cancer, and the risk calculus is different
Each case is treated individually: cardiovascular risk, quality of life, personal values, receptor status
What caused the breast cancer matters: for most women, it was not their natural reproductive hormones. Environmental endocrine disruptors, obesity, inflammation, and other factors are more often implicated
“I always ask women: what did your oncologist say caused it? They say they don’t know. Then I ask: what do you think caused it? We have to address the underlying issues that caused the cancer. Reproductive hormones weren’t the villain.”
Neither physician is recommending that every breast cancer survivor go on hormones. They are recommending that women be given the full picture and allowed to make their own informed decisions.
FAQ: Bioidentical Progesterone in Menopause
Q: Do I need progesterone if I had a hysterectomy?
A: Yes, according to Dr. Felice Gersh and Dr. Anna Cabeca. The traditional view is that progesterone is only needed to protect the uterine lining. But progesterone has receptors throughout the neurological, cardiovascular, immune, and musculoskeletal systems. Women without a uterus still benefit from progesterone for brain health, sleep quality, mood, anti-inflammatory effects, and its interaction with estradiol and other hormones. The uterine protection argument was never the whole picture.
Q: What is the difference between progesterone and progestin?
A: Progesterone (P4) is bioidentical — it has the same molecular structure as the hormone produced by the human ovary. Progestins (such as medroxyprogesterone, levonorgestrel, or norethindrone) are synthetic versions with a different molecular structure. They behave differently in the body and have been associated with increased health risks in studies like the Women’s Health Initiative. Progestins are found in hormonal IUDs (like Mirena), many birth control pills, and older hormone replacement formulations. An IUD containing levonorgestrel is not the same as progesterone.
Q: Should I take oral progesterone every night or cyclically?
A: Dr. Felice Gersh recommends cyclic progesterone — two weeks on, two weeks off — for most postmenopausal women, to approximate the natural luteal phase rhythm. Continuous nightly oral progesterone converts approximately 80–90% of the dose to allopregnanolone in the liver, producing blood levels far above what a woman would ever naturally have. While some women tolerate and prefer nightly oral progesterone, the long-term brain health implications of chronically elevated allopregnanolone are not yet established. This is a conversation to have with your physician, not a reason to stop medication without guidance.
Q: What is allopregnanolone, and why does it matter for menopause?
A: Allopregnanolone is a progesterone metabolite produced primarily in the liver when oral progesterone is taken. It binds to the GABA-A receptor in the brain and produces sedating, calming effects — similar in mechanism to Valium. In appropriate amounts, it supports sleep and mood and may be neuroprotective. However, at doses produced by 100–200mg oral progesterone nightly, blood levels can be 2.5 to 5 times higher than what a woman would ever naturally produce. Synthetic allopregnanolone is classified as a controlled substance. Some women describe feeling “drugged” on oral progesterone; when stopped, they report mental clarity returning. This does not mean oral progesterone is always wrong — it means the mechanism and dosing deserve more attention than they currently receive.
Q: What is the best way to take bioidentical progesterone?
A: There is no single best route — the right delivery method depends on whether you have a uterus, your individual absorption patterns, your symptoms, and your physician’s monitoring approach. Vaginal and rectal delivery bypass most first-pass liver metabolism, producing actual progesterone in the blood rather than primarily allopregnanolone. Doses of 200–400mg vaginally are used in Dr. Gersh’s practice. Transdermal (through the skin) also works but requires closer monitoring. Oral progesterone is an option but produces predominantly allopregnanolone rather than progesterone. All approaches require blood level monitoring.
Q: Can I take hormones after breast cancer?
A: This is a nuanced question requiring individualized informed consent. According to Dr. Gersh and Dr. Cabeca, the evidence does not clearly show that bioidentical hormones cause breast cancer recurrence — and the biggest documented driver of recurrence is inflammation, not hormone therapy. At least 12 studies now indicate that estradiol does not increase breast cancer risk and may reduce it. Progesterone down-regulates the estrogen receptor that drives tumor growth. Women who are not in active treatment, do not have known metastatic disease, and have been fully informed of both the evidence and its limitations may choose to use hormones. Every case is individual. The goal is informed consent, not blanket avoidance.
Q: Does progesterone cream (transdermal) actually absorb through the skin?
A: Yes. Progesterone does absorb transdermally. The limitation is that transdermal absorption does not always show up clearly in standard serum blood tests, though it does appear in salivary and urinary measurements. For women without a uterus, transdermal progesterone is generally considered appropriate. For women with a uterus who are relying on progesterone for endometrial protection, the data on transdermal’s effectiveness for that specific purpose is less robust than vaginal or rectal, and additional monitoring is recommended.
Q: What are the signs that progesterone might be right for me?
A: Women who may benefit from progesterone support include those experiencing anxiety, poor sleep, brain fog, low mood, irritability, night sweats, or symptoms associated with hormonal decline. This applies whether or not they have a uterus. Both Dr. Gersh and Dr. Cabeca evaluate the full picture: current hormone levels, symptoms, organ system health, how long since menopause, and individual goals. They do not prescribe progesterone based on uterus status alone. Finding a physician trained in bioidentical hormone therapy and integrative medicine is the recommended starting point.
Resources Mentioned
- Dr. Anna Cabeca’s Balance cream (progesterone and pregnenolone)
- Fournier study / EPIC trial on progesterone vs progestins and breast cancer outcomes
Women’s Health Initiative (2002) and its long-term impact on hormone research
Connect with Dr. Felice Gersh
Dr. Gersh’s books: PCOS SOS and Menopause: 50 Things You Need to Know
Connect with Dr. Anna Cabeca
Instagram
YouTube
TikTok
Facebook
Note: For women interested in working with a physician who takes this approach, the Integrative Medical Group of Irvine is Dr. Gersh’s practice. Dr. Cabeca’s Girlfriend Doctor Club community and program resources are available at dranna.com.
