The Hidden Thyroid Link to Infertility and Miscarriage

Beyond the Thyroid – Episode 37: The Hidden Thyroid Link to Infertility and Miscarriage

In this episode of Beyond the Thyroid, Dr. Dana Gibbs uncovers the often-overlooked role of subtle thyroid imbalances in fertility challenges and early pregnancy loss. She explains how even “normal” thyroid labs can miss critical dysfunctions that affect ovulation, implantation, and fetal development.

Dr. Gibbs discusses:

• Why conventional thyroid testing overlooks key markers
• How thyroid autoimmunity and reverse T3 can impair fertility
• The importance of individualized thyroid hormone management before and during pregnancy
• A patient success story: overcoming multiple miscarriages with proper T3 therapy

If you’ve struggled with infertility or recurrent pregnancy loss, this episode offers science-based insights and hope.

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Episode Highlights:

00:00 Introduction to Infertility and Thyroid Issues
02:26 Understanding Thyroid Hormones and Fertility
05:23 The Role of Autoimmunity in Thyroid Dysfunction
06:55 The Importance of Reverse T3
12:25 Symptoms and Diagnosis of Thyroid Imbalance
16:17 Case Study: Overcoming Infertility with Thyroid Treatment
20:55 The Benefits of T3 Therapy
25:01 Conclusion and Next Steps

✨ When thyroid function is optimized, fertility can thrive. Tune in now!

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✉️ Email Dr. Gibbs at drgibbs@DanaGibbsMD.com or visit https://www.danagibbsmd.com/ for more information.


Thank you so much for listening! Tune in on the next episode.


The medical information provided in this episode is intended for informational purposes only and should not be construed as medical advice. Always consult a qualified healthcare provider regarding any medical questions or concerns.

Transcript

dana-gibbs-md--she-_2_09-30-2025_133812 0:00

Hi everybody. Welcome to episode 37 of Beyond the Thyroid. Today begins the first in a three part series about infertility and thyroid, and this is one of the most heartbreaking issues that I see in my practice because even though most obstetricians are well aware that the thyroid is involved in fertility and pregnancy, very few understand the devastating consequences of thyroid imbalance, particularly the elevated reverse T three. In patients whose labs look normal, and by normal I mean of course, that their TSH and maybe their free T four are in range, but nobody has gone deeper. So if you've been struggling with infertility or repeated miscarriages and nobody has looked beyond your TSH, this episode may be the most important one you listen to. Because today I'm gonna show you why that happens, what the missing labs are, and how. Hidden thyroid dysfunction can sabotage both conception and early pregnancy.

1:15

You're listening to the Beyond the Thyroid podcast. I'm your host, Dr. Dana Gibbs. I'm an ENT surgeon and hormone specialist. For years, I struggled with my own unrecognized thyroid problems before and even after I was regularly performing thyroid surgeries. Then, one day, I learned something that turned my health around and opened my eyes to the limits of mainstream medicine in treating more subtle thyroid abnormalities. I spent the next 20 years fine tuning my hormone expertise in disorders like Hashimoto's disease, perimenopause, and stress related illness. Come join me as I share this new approach to hormones that empowers you to take control of your own thyroid and hormone imbalances. Let's dive in.

dana-gibbs-md--she-_5_09-30-2025_134121 2:08

Imagine the joy of seeing a positive pregnancy test only to have it be followed a few weeks later by heart rate again and again. You go through the same test, you hear the words, everything looks fine. But what if the one test you really needed, the one that could explain it all was never ordered. So today I am gonna walk you through three key reasons why even a normal TSH and T4 may be hiding a thyroid problem that's contributing to early pregnancy loss and infertility. So thyroid hormones regulate ovulation implantation, early embryo development, and placental growth. T3 receptors are present in the ovaries, in the uterus and the placenta. So even subtle thyroid imbalances affect menstrual cycles, the length of your luteal phase, uterine lining, thickness and egg quality, and even ovulation. So in early pregnancy, the embryo can't make its own thyroid hormone until about 12 weeks until then, it depends entirely on the maternal supply. So when thyroid activity and function is borderline, or when the hormones are present in the blood, but they're not being activated properly in the tissues, reproduction is probably the first system that's gonna suffer. But what I find is when people come to me and I ask them, they've had many other symptoms all along. So why does normal TSH not necessarily mean your thyroid is completely fine. Well, most doctors use the TSH test as often the only screening tool that they use for thyroid disease. But TSH is a brain signal, not a thyroid hormone. It is coming from the pituitary, which is a part of your brainstem, and it's your message to the thyroid gland,"Hey, make more, make less." Like a thermostat you know, turn the thermostat off and on. But what if that thermostats and that heater are in a small corner of your house? And what that says on that thermostat has really nothing to do, whether it's actually warm back in the bedroom or not. So you can have a perfectly normal TSH and still be hypothyroid in your body tissues. That's because the problem may not be in your thyroid gland at all. It may be in how your body processes and uses the thyroid hormone after it leaves the gland. And in pregnancy, the margin for error is even tighter. Even mildly abnormal thyroid levels can signal increases in miscarriage, impair fetal brain development and reduce the chances of implantation. But unless your TSH is outside the range that the gynecologist recommend, which is above two, generally, many providers are not gonna test further. And if it's above two, they're still only gonna give you usually levothyroxine and they won't check the markers that show whether your thyroid hormone is being activated or not. So this is one of the biggest missed opportunities in reproductive medicine, in my opinion. So, the role of autoimmunity is fairly strong here because even if your thyroid hormones are normal, your immune system is probably still sabotaging fertility, and the most common cause of autoimmune disease is autoimmune thyroiditis or Hashimoto's disease, and that's also the most common cause of hypothyroidism in women, and it's frequently present for 20 years or more before your TSH goes completely abnormal because of how slowly it damages your thyroid hormone production. In Hashimoto's disease, the immune system is producing antibodies which are anti TPO and antithyroid globulin, and they attack the thyroid gland, but there's also a cellular process that's attacking the thyroid gland. And possibly other tissues in the body that we're not even sure. But people who have those positive thyroid antibodies, even if their thyroid function is pretty normal, have a significantly higher risk of miscarriage IVF failure and infertility. So if you've had more than one miscarriage, or you've been trying to conceive for over a year, it's essential to know whether or not you have Hashimoto's thyroid antibodies. This test is pretty simple, it's inexpensive and it's usually covered by insurance. And a lot of your doctors are now getting savvy and they're gonna order that, but then they'll look at that normal TSH and they'll go, well, there's really nothing we can do about this. Suck it up. But there's another test, and it's one that almost nobody orders called reverse T3. And in order to understand why reverse T3 matters, we need to talk a little bit more about what happens to thyroid hormone after it leaves your thyroid gland. So remember we talked about the thermostat and the heat's coming up out of that one heater, but maybe it doesn't get to the rest of the house, the rest of your body, so to speak, and it certainly doesn't get turned into active heat, other places in your body or active metabolism. So in order for that to happen, you have to have T3 that's active at the source and not being blocked or turned down by something else. T3 is made a little bit in your thyroid gland, maybe 10% of the thyroid hormone that comes out of your thyroid is T3, and that's enough to supply about 20% of your need for T3 if your thyroid is normal. Now, if you have thyroid damage because of Hashimoto's or because your thyroid is gone or some other reason, you're definitely not gonna have enough T3, and now you're a hundred percent relying on conversion of T4 to T3 out in the body tissues, and if you don't have enough T3 because you're not converting, then it's very likely if you do already have adequate T4, that what's happening to that excess T4 that's not getting converted to T3 is that it's getting made into something called reverse T3. And reverse T3 is also made a tiny bit inside the thyroid gland. And if you look at how thyroid hormone overall comes outta the thyroid gland, it's about a 10 to one ratio of T3 to reverse T3, and the rest of the T3 that you need has to be converted in your body tissues. Now your body can make reverse T3 intentionally for several different reasons. In times of stress or illness or starvation, it's an adaptive way to slow down your metabolism and conserve your energy. But sometimes it can happen because you have a genetic defect. Or because you have Hashimoto's disease, it's keeping the brakes on your system and that'll leave you having symptoms. You can be exhausted, foggy brained And then all the other symptoms that go with hypothyroidism plus infertility, irregular periods, and a tendency towards a miscarriage in the first trimester. That elevated reverse T3 can do that. Even if the amount of T3 that you have floating around in your blood looks pretty normal. And we don't know exactly why that happens, but there's lots and lots of evidence that show that certain illnesses where reverse T3 is high, impairs your metabolism. It impairs your ability to generate heat and ability to grow new cells. Lots of different things. That's why I calculate a total T3 to reverse T3 ratio. It is the single best indicator of whether thyroid hormone is actually doing its job in your body tissues. And a healthy ratio is right around 12 and anything too above or too below 12 is probably okay, but less than 10 means your body's inactivating thyroid hormone instead of using it. And if it's less than 9, you can definitely say that there is not enough thyroid activity happening in your body tissues. Now if you are having it be higher than 14, yeah, if you're a teenager, higher than 14 is probably okay, but in a woman who's trying to get pregnant, 14 can mean over medication or stress related imbalance. And that is not the only test I order, of course, on these folks, they also need to have free hormone levels that are well within the normal range. So who is likely to get this problem? Well, we already mentioned too. One of them is people who have Hashimoto's disease. There's also people who are under chronic stress. There's women who have insulin resistance or metabolic syndrome, and then anybody with some kind of chronic illness or inflammation. And then this genetic thing I was talking about where about 16% of people of British descent were found to have a mutated diastase enzyme, and that's the enzyme that makes T4 into T3 out in your body tissues. So if you have that genetic variant then you're making way more reverse T3 than you should, and about 30% less T3 than somebody who does not have that variant. So the workup that I do when somebody comes to me with those symptoms and their miscarriages and their normal TSH or even if it's a little elevated, or even if it's, I don't care what their TSH is, if they've got those issues and they don't have to be on thyroid medicine. They can be off thyroid medicine or on thyroid medicine. Here's how I start. So I'm looking for symptoms. I'm looking for brain fog, cold hands, weight gain, menstrual irregularities, low libido, poor sleep, poor quality skin and hair, hair loss on the top of your head and then fatigue. Fatigue is absolutely the number one symptom, and of course it's very vague and lots of things can cause fatigue. Even, for example, having infertility treatments will cause fatigue. The next thing I'm looking for on the physical exam would be low blood pressure, low body temperature, sluggish reflexes, and cold, hands and feet. Those are really, really common. And then those abnormalities of skin and hair, which you can see on a person. You know, if your hair is so thin that you can see your scalp through the top of your hair, then that's not normal. Most people who come to me have already had their Hashimoto's antibodies tested, and so I will test those if they haven't had it. If it's been a really long time, I might test it to see if we can figure out how active their Hashimoto's disease is. And then the next are the big five thyroid tests, which include TSH free T4, free T3, total T3, and reverse T3. The next thing I do is I calculate this total T3 to reverse T3 ratio. You must use the total T3, not the free T3. Free levels don't account for the binding protein differences and give very misleading results. They're not predictive and you cannot use them to guide therapy particularly, although, high reverse T3 all in and of itself can give you clues that something is not right. So I do tend to do a larger lab panel and that includes a lot of different metabolic markers, including iron, ferritin, glucose and insulin markers, sometimes adrenal testing and cortisol if that history is suggesting that complete stress overload, but not always. But so basically it's a basic metabolic workup that anybody who's getting a full physical is gonna get. So this gives me a real picture, not just of whether the thyroid gland is producing enough hormone, but whether the body is either activating it if it's above 12. Or if it's shutting it down, if it's below 10 or below 9. I wanna speak directly to many of you who are listening. So many women I see are trying to do it all. We've been told we can do it all. We should try to do it all. So we're balancing a busy career, raising kids, managing a household, often caring for our aging parents, all while trying to be a supportive partner and maintain friendships, and then try to get pregnant too. These women are really being pulled in every direction. They feel exhausted. They chalk it up to normal life. I was this way for sure. Many of them don't even realize that something is medically wrong, but who wouldn't be tired under all that pressure, right? But here's the truth. While stress and sleep deprivation and overwork absolutely drain our energy, they can also cause this thyroid metabolism flip into the pattern that's producing the high reverse T3 and the less active T3. So your body's literally breaking your metabolism. It's saying,"Hey, you are trying to do too much", and sometimes that can get into a vicious cycle where even if you take a break, you don't get better and no amount of caffeine or willpower is gonna fix it. So if it sounds like you, please know, you don't just have to accept feeling this way, there may be this clear medical explanation, this thyroid imbalance. Alright, so let's talk about this woman and I'm gonna call her Casey. She was 35. She came to me. Already having been diagnosed when she was like 17 with Hashimoto's disease, she was already taking levothyroxine. And on paper her labs looked fine. Her TSH was well in the normal range about two. And her OB had measured that and reassured her that her thyroid wasn't a problem, but she had a lot of symptoms. She was exhausted, foggy, struggling with her weight, and most heartbreaking of all she had. Already experienced three and possibly four early miscarriages. She told me her body was betraying her. She was doing everything right. She was eating gluten-free, low carb, you know, low processed food diet. But month after month, either she didn't conceive or when she did, she was miscarried early and nobody had ever looked deeper into things. And because she was conceiving, they didn't offer her IVF either. So when I ordered my thyroid panel on her, including that total T3 to reverse T3 ratio, the real problem became clear because her number was four. Number was way too low, even though she had plenty of T4 in her system and she was taking levothyroxine, her body was not converting it into active T3, and it was being shunted into reverse T3, effectively putting breaks on her metabolism, not allowing her fetus to start developing properly and it was putting brakes on her reproductive system. So when I did her workup, we did a couple of things that were very, very important and that are kind of a keystone of what I recommended. And the first one of those is that you need to take levothyroxine twice a day and you take half as much. As a matter of fact, a lot of times you can take less than half. As much as your usual dose, but you take it two times a day and what that does is it stops you from having this temporary, very high level of T4, which is another process that puts a break on the conversion of T4 to active T3. So that was the first thing we did. And then I redid her lab test and things were a little bit better, but at this point, everything was totally normal except for that reverse T3 number. It was very high. I think it was 32 which is crazy and all the rest of her numbers were normal. So what we did is gradually over a period of time I started reducing the amount of T4 that she was on and giving her directly liothyro9, which is the generic version of T3. And when you give Liothyro9, once again, I'm giving that twice a day. You're already taking your levothyroxine twice a day. It's very easy to give Liothyro9 twice a day. The reason it's dramatically important to take Liothyro9 twice a day is because it is very short acting. It's more like tylenol than it is like Naproxen, for example. You don't take it once a day, you take it two or even three times a day. And as we gradually increased the amount of T3 she was taking and lowered the amount of T4 she was taking, her energy returned, her cycles became more regular, and her cycles started getting more healthy looking and her labs showed a healthier ratio. She got married, she went on her honeymoon, and guess what, A couple months later she called me with the news. She was pregnant again, and this time her pregnancy continued to progress normally. She was overjoyed, of course, and we monitor very, very carefully. We check every one month because what can happen once you get pregnant is that the binding proteins change dramatically in your body. And so then she actually needed to go back up on her levothyroxine. While keeping the T3 amount the same, she needed more. T4. T4 is crucial for the fetus. And you definitely don't want their reverse T3 number to get too low. So it's really, really important to have somebody who really knows what they're doing. If you are monitoring T3 T4 treatment during a pregnancy. So let's talk a little bit about why T3 therapy can change everything for people. So, most thyroid medicine is T4 only. It's levothyroxine, it's Synthroid, it's Tyrosine, it's Levoxyl. It relies on your body tissues to convert T4 to T3, T3 being the active hormone that actually does all the things that your body needs thyroid to do. But if your body is shunting T4 to reverse T3, then more T4 only makes that problem worse. Because T4 only has two ways that it can go, it can be made into T3 or it can be made into reverse T3. And if it's being made more, and the higher it gets, the higher that signal gets to make reverse T3. Because your body thinks it's seeing too much. It's seeing hyperthyroid. That's your brain thinking that. And so your thyroid kicks down, it lowers your TSH, and it takes that T4 and it makes it into reverse T3 to put the brakes on your metabolism. And my mentor uses an analogy. He said, when you have high reverse T3, even if your T3 is pretty normal, it's like going down the freeway in first gear with the parking brake on, it's gonna burn up your engine anyway, so, and you don't feel good and you don't get anywhere. So when you add liothyro9 and take away some of the levothyroxine, what you're getting is you're bypassing that block conversion. You're giving what your body needs directly, and as you lower the T4, you have less signal to make reverse T3, you have less precursor to make reverse T3. So you dose this carefully and you dose it twice a day, sometimes three times a day, it really dramatically improves energy, mood, metabolism, fertility. If you have a goal of weight loss, it makes it much easier to get that done. And for women struggling with infertility, it can restore your cycles. It restores ovulation, it improves uterine receptivity, and it lowers that miscarriage risk. It also increases the IQ of your fetus that's delivered to term. There are studies that show these things. It's crazy. So, if you have faced infertility or recurrent miscarriages and you've only had your TSH checked, here is what you need. You need this complete panel, the TSH, the free T4, the free T3, and the total and reverse T3. You need thyroid antibodies, thyroid peroxidase, and anti-thyroglobulin antibodies. If you've never had that, and then you need to check that total T3, reverse T3 ratio if it is below 9, you have a problem with your conversion. So, if this sounds like your story, I want you to know you're not alone, you're not crazy. This is exactly why I built my practice. This is exactly why I created the Thyroid Checkup Program. So if you'll go to my website, you can read about these things. That's danagibbsmd.com/checkup. You can learn more, you can get on the priority wait list. You can make an appointment for a free discovery call, and I would love to talk to you about your issues. So instead of years of frustration and dismissal, you can finally get the right labs, interpreted the right way in a clear path forward. So imagine seeing that positive pregnancy test come back and believing that this time it's gonna stick. Imagine finally knowing why your body is betraying you and having a plan to fix it. Imagine the relief of understanding your labs and having real answers to why you felt this bad all this time, and the joy of moving forward with real hope. It is possible, and it starts with looking beyond the TSH. All right guys. That was it for today. This is, like I said, it's part of a three part series, so I'm gonna have two guests upcoming, both of them who are experts in infertility, and we are gonna have so much fun talking to these folks. So check those next few episodes out as well, and I will leave you until next time. Thanks for listening. Bye-bye.

25:30

Thank you for listening to this episode of Beyond the Thyroid. If you found this information valuable, it would mean so much to me to take a few seconds and give the podcast a five star review. It helps other people who need this information find the show and it's really easy. Just search and click on the name of the show, Beyond the Thyroid, and scroll to the bottom to ratings and reviews. I truly do read and appreciate. Remember, when it comes to hormones, there will always be more to discover, so follow the show so you get the next episode as soon as it's released. And if you or someone you care about needs a caring doctor to help figure out how to heal hormone problems that other doctors have dismissed, check out my website at www. danagibbsmd. com. And if you're not a physician, please keep in mind, while I'm a doctor, I'm not your doctor. The content of this podcast is my opinion and it's for educational and entertainment purposes only. This is not meant to be individual medical advice and you should consult your own physician for any medical issues or diagnoses that you may have. I look forward to continuing this journey with you beyond the thyroid.