158. What Progesterone Is Really Doing for Your Whole Body

Most women know progesterone as the pregnancy hormone. But progesterone is doing so much more than preparing your uterus for a baby. It protects your brain, builds your bones, calms your nervous system, supports thyroid conversion, and keeps estrogen in check every single month. And when it is low — which it is in more women than anyone realizes — you feel it everywhere.

In this episode of Cycle Wisdom, Dr. Monica Minjeur makes the case for progesterone as one of the most important and most underappreciated hormones in a woman's long-term health — far beyond fertility. Through Diane's story, a 38-year-old with regular cycles who had been living with poor sleep, premenstrual anxiety, heavy periods, and early bone softening that nobody had connected to her hormones, you will see what identifying and treating low progesterone can change.

You will learn:

• What progesterone actually does across every major system in the body — brain, bone, cardiovascular, thyroid, and reproductive health
• Why ovulating does not guarantee optimal progesterone — and what levels you should actually be aiming for
• The critical difference between bioidentical progesterone and synthetic progestins — and why that distinction matters enormously for your long-term health

If you have been told your progesterone is fine without a timed mid-luteal lab draw — or if your symptoms have been explained away as stress or personality — this episode is for you. Learn more or schedule a free discovery call at radiantclinic.com.

Transcript

Speaker 0:02

Most women know progesterone as the pregnancy hormone, but progesterone is doing so much more than just preparing your uterus for a baby. Progesterone also protects your brain, helps to build your bones, calms your nervous system, and keeps estrogen in check every single month. When progesterone is low, you feel it everywhere. Today, we're talking about what progesterone actually does and why optimizing it is one of the most powerful things we can do for a woman's long-term health. I'm Dr. Monica Minjeur, the host of Cycle Wisdom, where we help women and couples restore hormonal balance and reclaim their wellbeing through personalized healthcare grounded in clinical excellence. Let's start off, as always, with a patient story, and we'll call her Diane. Now, Diane came to see us at about 38 years of age. She was done having children, and she had regular cycles, but she had been struggling for years with poor sleep, anxiety that happened before her menstrual cycle began, and heavy periods. She also felt as though her brain was constantly spinning with what she called the hamster that never goes to sleep. Now, Diane had been managing these symptoms for years, and in fact, she stopped thinking they were a problem. She just assumed this was her personality. This was what she had to deal with, with the changes in her body. And it wasn't until her sister was diagnosed with osteoporosis at age 45 that Diane came in asking whether her hormones might also be playing a role for her symptoms. She was primarily concerned about her bone health and actually came in asking for estrogen therapy. When we dug a little bit deeper, we talked through all of the other pieces with her other symptoms and recommended a full evaluation so that we could see the big picture. As always, we started with cycle charting, and although Diane's cycles confirmed ovulation, she had a really short luteal phase. So from the time she ovulated until her next period began was only about nine days. Ideally, we're looking for that to be somewhere closer to about 12 days. We also had checked some lab work. In the mid part of her luteal phase, her progesterone was only at 6.8. Ideal should be at least 15 to 17. And we also did a complete bone density scan with her sister's history. Now, although Diane did not have any significant bone loss yet, she did have some early osteopenia or softening of the bones, which was unusual for her age, especially since she had been having regular cycles. We also found thyroid dysfunction, a lower than normal T3, which is the active form of thyroid hormone, and this is very common to find running alongside a low progesterone. We worked through all of these pieces at the same time and systematically in order to help support Diane's progesterone levels, support the thyroid function, and help with the other lifestyle pieces that she was struggling with. Over the course of the next two cycles, Diane's sleep completely normalized and her premenstrual symptoms had changed dramatically. Follow-up bone density scan two years later showed stability in her bone loss, and more importantly, we had a clear plan for what needed to happen with keeping her hormones well-balanced and stabilized going forward as she headed into her next transitions of life. Now, progesterone is primarily a hormone that most of us have heard about, but it is also the most commonly deficient hormone we find in reproductive age women. It is rarely evaluated outside of a pregnancy or infertility evaluation unless you are working with someone who understands how progesterone plays a role with all the different systems in your body. Progesterone is primarily produced at the time of ovulation by the corpus luteum. Now, your corpus luteum is kind of the shell that is formed after your body releases the egg. And if you don't have an ovulation event, you don't have a corpus luteum, there is no meaningful progesterone production. So it's incredibly important to be evaluating progesterone, and this is why we talk about it is so important to have that ovulation event because if you don't, it is nearly impossible for your body to fire off enough progesterone. Something that most women don't know but is incredibly fascinating is that the function of progesterone extends to virtually every system in your body. Your brain, your bone, your cardiovascular system, your thyroid, your immune system, and of course, your uterus, ovaries, and reproductive organs. In fact, a 2026 literature review done through the University of British Columbia confirmed that an ovulatory cycle, so if you're not ovulating, and the subsequent decrease in progesterone was found in over 25% of all menstrual cycles and linked this with early cardiovascular disease, increased risk of fragility fractures or fractures of the bones from that bone softening or bone density loss, increase in dementia risk, and increased cancer risk. This evidence rarely reaches women, and this is why it is so important that we talk about it. Progesterone is not just about getting pregnant. It's not just about fertility. It's not just about prevention of miscarriage. It is about overall health, and that is why it is so incredibly important that we talk about this and that you understand what the symptoms are that you need to watch out for Now, before we dig a little bit deeper, I do wanna address a couple of myths that we oftentimes hear. One is, "Well, I'm ovulating, so my progesterone must be fine," or even, "I've had a lab test done and my doctor said it was normal." Now, ovulation confirms that a signal was sent, confirms that progesterone is firing, but it doesn't confirm that we have an optimal progesterone level. And we'll talk a little bit more about this later, but really at a minimum, we need to be looking for a progesterone level at least in the range of 15 to 18 nanograms per milliliter. If you are trying to conceive, we find that better conception rates with miscarriage prevention actually show a progesterone somewhere in the 19 to 30 range nanograms per milliliter. And again, important that this is timed seven days after ovulation. So just a, quote-unquote, 'normal progesterone level' is not going to be enough. And then the other big misconception that we often hear is, "Well, I'm on birth control and it's a progesterone-only birth control. Isn't this the same?" All of the hormonal birth controls that are out there are synthetic progestins. A progestin is a synthetic form of progesterone. They are molecularly different. Your body sees them as different. And the biggest issue here is that progestins, such as are in hormonal birth control pills, as well as those that are in IUDs, a Depo shot, um, or even the implants, all of these synthetic progesterones do not convert into allopregnanolone. Allopregnanolone is the important hormone that your body needs in order to have that neuroprotective, bone-building, and cardioprotective properties. So if you're taking a synthetic progestin, you don't get the impacts or the benefit of allopregnanolone. Versus if you are taking a bioidentical progesterone, that does convert to allopregnanolone, both if you're taking it as a pill or what is produced naturally by your body. So this is why it is so incredibly important to understand not only what your particular prescription is, but how you're taking it, how the timing works, and we'll get into all of that next So let's start with what does progesterone do? And this is as full of a list as I can provide right now. Certainly, there may be things in the future that we find. Now, we've talked a lot about progesterone's impact on the reproductive system. It helps to prepare the lining of the uterine wall for implantation. It supports early pregnancy. It supports the placenta throughout all of pregnancy and helps to maintain that uterine environment until the placenta can take over. We also know that progesterone is incredibly important for being a signal of how adequate was the quality of ovulation on any given cycle. So for our couples we're working with who are trying to conceive, we are checking progesterone and estradiol levels every single cycle to make sure that we are optimizing the quality of that ovulation event. Progesterone also has a significant impact on the brain. And again, as I just mentioned, it's converted to allopregnanolone. This is a neurosteroid that binds to GABA receptors. Now, a lot of people know of GABA receptors as kind of your feel-good, your happy hormones that are going on in your brain. And when that binds to those GABA receptors, it helps to produce a very calming impact, tends to decrease anxiety, and oftentimes helps to promote sleep. This is also neuroprotective after brain injury, and there are actually some fascinating studies being done even in humans right now of looking at the impacts of giving allopregnanolone or even progesterone directly after individuals have suffered brain injury, whether from a traumatic brain injury like a car accident or a stroke, and really looking at how does this protective hormone help to rebuild how our brain tissue is functioning, which is fascinating. We also know that progesterone has an impact on bone. So as was noted with Diane and her sister, progesterone deficiency can cause problems with the bones. Progesterone stimulates cells called osteoblasts. Osteoblasts are designed to be a bone-building cell, and this is independent of estrogen. Now, we know that we need estrogen in order to have good bone density, but we also need to have progesterone. Women that have chronically low or absent progesterone, meaning if they're not ovulating at all, have measurably lower bone mineral density. And this is why it's so important to make sure that levels are adequate, because by the time we hit menopause and estrogen starts to dramatically drop, we don't want to already go into that menopause transition with low bone density. We want to make sure that the bones are nice and strong throughout. Cardiovascular system is also incredibly important and relies on progesterone to help support the relaxation of your blood vessels. This can also help to improve cholesterol, blood pressure, and helps to counteract the impact of estrogen that it can have on your vascular tissue. As I mentioned with Diane as well, thyroid also is really going to have a big role in how it responds to progesterone. Progesterone helps to support the conversion of T4, which is the thyroid hormone produced by our thyroid gland, helps support that converting into T3, which is the active form of thyroid hormone. We very, very, very frequently in our practice will see low progesterone alongside with a functional T3 deficiency, and this is part of the reason why when we are looking for these things, we want to restore both of them in conjunction with each other. Because oftentimes as we restore the progesterone, thyroid is helped, and then we're able to oftentimes come off of the thyroid medication when that progesterone has stabilized. And finally, progesterone is important for protection of the endometrium or the uterine wall lining. It works to offset the estrogen that is going to be responsible for increasing the thickness of the uterine wall lining. Now, if we don't have any progesterone to oppose or kinda push back that estrogen, it can drive increased thickness of that uterine wall lining over time, which can also increase cancer risk. This is why we talk about in our post-menopausal patients that if you still have a uterus and you're on estrogen therapy, you must also be on progesterone therapy at least 10 days per month, because we always want to be offsetting what's happening with that endometrial thickness. So how do I know if my progesterone is adequate? As I mentioned previously, we are looking to get a lab draw approximately seven days after ovulation. For most women, that is approximately when your progesterone levels will be at their highest point, and this is really the gold standard for assessment across all restorative reproductive medicine doctors that I talk to. A level in the range of 15 to 18 nanograms per milliliter is c- generally considered adequate. Below seven or eight is typically going to be insufficient for implantation support, regardless of whether ovulation occurred. Many, many times we'll see that a day 21 progesterone level is checked, and if it's anything above three, the box gets checked and you're told your progesterone is fine, you have ovulated. That is not the question we're asking here, though. We are not asking, did ovulation occur? We're asking, was it an optimal ovulation? Was it a high quality ovulation? And is my body responding with the appropriate progesterone levels needed in order to support overall good health and fertility, if that's my intention? If you haven't yet gotten your labs drawn or if you're waiting to start working with a doctor, other things that you may see that could indicate low progesterone would be signs of a short luteal phase. So from the time you ovulate until your next period begins, if it is less than 12 days, and definitely if it's less than 10 days, almost always that is going to be tied to a low progesterone level. We oftentimes will also see PMS symptoms, so especially problems with your mood or anxiety in that week or two leading up to your menstrual cycle, oftentimes that can be linked to a low progesterone level. And we also will see premenstrual spotting. So if you have bleeding or spotting or even some brown discharge that happens in the few days leading up to an actual flow beginning, that's also a very common indicator that you may have low progesterone. Other symptoms that can correlate with that low progesterone, especially during your premenstrual phase, are going to be increasing anxiety, troubles with sleep, breast tenderness, and premenstrual headaches. If you start to track out those symptoms and you're consistently seeing that they are falling in that week or two leading up to your period beginning, really important that you would get those progesterone levels checked. Other unusual bleeding signs that we can see are if you have heavy periods. Oftentimes this will happen because you have too much estrogen in relationship to a low progesterone. Now, in some cases, that estrogen may actually be normal, but if your progesterone levels are too low, that allows that uterine wall thickness to be increased, which can then create problems with heavier periods or, in some cases, even to have spotting in the middle part of your cycle when we normally wouldn't see that. Now we can start to see these changes in progesterone really at any age. But if you are having less consistent ovulation or no ovulation at all, this is going to be a much bigger deal. And this is why it's so important that we are charting cycles even if you're not trying to conceive, because we want to be able to positively identify that ovulation is happening. We can see luteal phase shortening begin even in your late 20s, but generally will have a meaningful progesterone decline in your late 30s as anovulatory cycles become more frequent. Oftentimes, this happens years before estrogen shifts or even before you would see a difference in your cycles. Other things we know contribute to low progesterone at any age are going to be things like chronic stress, undereating, overexercising, thyroid dysfunction, elevated prolactin levels, PCOS or now PMOS, and perimenopause. Perimenopause is really a clinical distinction of seeing that progesterone declining first that then leads to a relative estrogen dominance that can oftentimes worsen heavier periods, PMS, anxiety, and sleep disruption. And this is why it's so important to be watching for this at any stage. Now, when it comes to treatment, it's critically important here that we would identify what is a natural or bioidentical hormone versus a synthetic progesterone, which is also known as a progestin. So let's start first with natural or bioidentical progesterone. This is molecularly identical to what the ovary produces. Again, a natural progesterone converts to allopregnanolone and exerts the full range of progesterone's effects. Basically, imagine your own body's hormones doing what they're supposed to be doing. That is the authentic situation that we want to encourage. Now, bioidentical progesterone comes by the brand name of Prometrium, or sometimes you'll see it on your pill bottle, it'll just say progesterone. If there are any other words or letters other than progesterone or Prometrium, you need to make sure you're asking your pharmacist and your doctor, "Is this the right thing?" So most of the other progesterones that are out there are synthetic progesterones or progestins. This is primarily what is found in hormonal contraceptives and even in some hormone replacement therapies. Oftentimes, these are going to be called things like medroxyprogesterone or hydroxyprogesterone, levonorgestrel, norethindrone, and others. If it doesn't specifically just say progesterone, likely you are getting a progestin, a synthetic form of progesterone. And as I mentioned previously, these progestins do not convert to allopregnanolone, so they have no brain impact. They have no anxiety impact. And in some cases, we find that they actually worsen mood and sleep. These synthetic progestins also do not build bone through that osteoblast pathway we talked about. And in fact, some formulations like the Depo shot or Depo-Provera are specifically associated with measurable bone density loss with long-term use. This distinction matters tremendously for treatment decisions, and most women are never told that it exists, which is why it's so important that we talk about it here. This is also the same reason that many women are not offered progesterone during their pregnancy is even if they've had a history of miscarriage. There was a synthetic progestin injection that was removed from the market back in 2023 after failing to show improvements in pregnancy outcomes. Unfortunately, the headlines read, "Progesterone doesn't help with pregnancy," without differentiating that it was the synthetic progestin that wasn't helping. And those studies weren't the same as looking at long-term clinical outcomes of women that used bioidentical progesterone to help with pregnancy support. Now, there are lots of different versions of bioidentical progesterone that are available, and depending upon your situation may make a difference as to the kind that is recommended for you. Now, we always wanna look at addressing the upstream cause. Are you having problems with not ovulating? Do you have stress or thyroid dysfunction or elevated prolactin? We always wanna be looking at treating those long-term factors whenever possible. But in most cases, we're going to recommend supplementing with bioidentical progesterone. Most commonly, we're going to use this as a pill to take by mouth or vaginally, as those are the evidence-supported choices because, again, they convert to allopregnanolone and deliver the full spectrum of effects as far as helping your whole body. Now, taking it by mouth oftentimes has the added benefit of helping with sleep and anxiety improvement. This is one of the most noticeable improvements that women oftentimes experience. We also know that supporting nutritional support does also tend to help with your own endogenous production of progesterone, so making sure that your vitamin levels are doing well. Vitamin B6, vitamin C, zinc, and magnesium, all of these help to support the function and the formation of the corpus luteum, and addressing these deficiencies can help with the long-term impacts on your progesterone intake. And I will just mention one final piece here on topical progesterone creams. Many of our patients come in taking these, and unfortunately, the systemic availability of progesterone taken topically is incredibly low. So we generally don't recommend the topical creams as a primary approach, especially when you have low progesterone levels and/or symptoms. In fact, these over-the-counter progesterone creams can be helpful for minor symptoms, but for meaningful long-term support, almost always you're going to need to take either the oral or the vaginal dosage. And more importantly, self-treating with an over-the-counter medication if you are not feeling better is not going to get you the measurable long-term outcomes that you need Now, if you are saying to yourself, "Well, look, I'm in my late 30s. My cycles are regular. Why should I even worry about progesterone? I'm not trying to get pregnant." And again, I would just go back to all of the symptoms, everything we talked through with Diane's situation at the beginning of this episode. The decline in progesterone oftentimes begins before your cycles become irregular or any obvious symptom shows up. Things like premenstrual anxiety, worsening PMS, heavy periods, or poor sleep oftentimes are explained by women as, 'Hey, I'm busy. Life is busy. My job is wild. My kids are crazy.' Like, all of these things that oftentimes get explained away, and the reality is, is that progesterone support can make a big difference if we treat it adequately now as far as what your long-term health looks like when we can optimize it. Imagine if progesterone was finally understood as the whole body hormone that it actually is. One that protects your brain, builds bone, calms your nervous system, and keeps estrogen in balance across decades of a woman's reproductive life and beyond. Low progesterone can be identified and addressed in a woman's 30s and early 40s before years of quiet insufficiency have accumulated into things like poor sleep, anxiety, and early bone loss. Imagine if every woman knew the difference between the progesterone her body makes and the synthetic progestins she may have been prescribed for years, and that that distinction could guide the care she received going forward. That is what informed, complete hormonal care looks like, and we would be honored to walk along this journey with you to discover your path to improving your health and promoting fertility

Speaker 2 23:55

If you're ready to work with our elite team of healthcare professionals, go to our website radiantclinic.com to schedule a free discovery call and learn more about our package-based pricing for comprehensive care. We are currently able to see people for in-person appointments in our Cedar Rapids, Iowa clinic or can arrange for a telehealth visit if you live in many different states across the US. Check out our website for current states that we can serve medical clients, and let us know if your state is not listed to see if we can still cover you there as we are constantly expanding our reach. Please note that our fertility educators are able to take care of clients no matter where they live. Thank you so much for listening to this episode. Please share this podcast with someone in your life who would benefit from our services. Remember to subscribe to this podcast for more empowering content that I look forward to sharing with you on our next episode of Cycle Wisdom