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Your Thyroid and Your Fertility

OK — let’s just get this out of the way: Um...what exactly is the thyroid?

The thyroid is a small gland located in your neck. Its job is to control your body’s metabolism — the process by which your body converts what you eat and drink into energy — through the hormones it releases. The thyroid creates and releases thyroid stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3).

While regular screening of thyroid hormone levels is not routinely performed, it’s recommended to get these tested if you have certain symptoms — more on these in a bit. Usually, an imbalance of the aforementioned hormones are to blame for these woes. In 2004, the U.S. Preventive Services Task Force (USPSTF) found insufficient evidence to recommend for or against screening for thyroid dysfunction in nonpregnant adults who were not presenting any symptoms. However, thyroid medication prescription rates in the United States have increased from an estimated 49.8 million in 2006 to 70.5 million in 2010.

In other words, your thyroid is something that’s worth paying attention to.

While many are aware that an imbalance can cause weight gain and fatigue, did you know that hormone imbalance can also impact your menstrual cycle and fertility? Regular thyroid hormone levels keep your reproductive cycle in check by sending a signals to our ovaries to ovulate each month. Thyroid dysfunction is much more common in women than men — at about a five to one ratio (we’re still not really sure why this is in the medical community).

Let’s start with an overactive thyroid

Hyperthyroidism (an excess of thyroid hormones) affects up to five percent of women. Symptoms of this condition can include unexplained weight loss, increased appetite, feelings of nervousness and anxiety, difficulty sleeping, fewer or lighter menstrual cycles, and increased sweating and heat intolerance.

In healthy, reproductive-aged women, luteinizing hormone (LH) peaks mid-cycle and signals the ovaries to release an egg — cue ovulation. But when the body produces too many thyroid hormones, LH can remain elevated during the entire cycle. With these chronically increased levels of LH, the “peak” is not drastic enough to signal the ovaries to ovulate. In other words, it confuses the body. Unusual ovulatory function can often lead to irregular or absent menstrual cycles. If you’re not ovulating, you can’t get pregnant naturally — your ovaries do not release an egg that can get fertilized by a sperm. See why this can impact fertility?

But hey, not to fear. With proper treatment, regular monthly periods (AKA optimized fertility) as a result of thyroid issues can often be restored. Treatment of hyperthyroidism varies depending on severity and provider preference. Many cases can be treated with certain medications you receive from your doc. You can also eat your way to a happier thyroid — stay tuned for these tips.

You know what’s next: an underactive thyroid

According to UpToDate, an online resource for clinicians, hypothyroidism (too little thyroid hormones) is found in two to four percent of women. Some common symptoms seen in hypothyroidism are weight gain, fatigue, constipation, feeling cold, thinning hair, pale skin, and increased or heavier menstrual bleeding.

When you have low levels of thyroid hormones, as you might have guessed, the body does not produce enough LH. Lower LH levels can inhibit that mid-cycle surge. As a result, your thyroid won’t signal to the ovaries that it’s time to release an egg. Without this signal, ovulation does not occur regularly, making conception difficult. In one study of a group of almost 400 women suffering from infertility, 24 percent of them were found to have hypothyroidism. Within a year of treatment for hypothyroidism, 76 percent were able to conceive.

Speaking of treatment, it typically involves a daily medication that supplies your body with the rest of the thyroid hormone it needs. However, treatment will vary from person to person, depending on severity. Typically, patients will be under close surveillance with initial treatment (labs drawn every six weeks to a few months) until a proper maintenance dose can be picked. Once a patient has a maintenance dose, thyroid labs will still need to be checked on a yearly basis. Overtreatment of the thyroid can occasionally cause something called “thyroid storm,” which can be dangerous. It’s important that treatment and management be done by a provider who is super familiar with the thyroid.

Is there any link between thyroid dysfunction and PCOS?

Excellent question — one I get frequently from patients. Thyroid hormone imbalance and polycystic ovarian syndrome (PCOS) often mimic each other in symptoms. Quick refresh: PCOS is believed to be rooted in hormonal imbalance, too, but primarily insulin and androgens (male hormones like testosterone). Symptoms can include ovarian cysts, absent or irregular menstruation, and excess hair growth in unusual places like the face, toes, neck, or chest.

In both cases, my fellow nurse practitioners and I often see irregular (or anovulatory) cycles (hence struggles with infertility) and, specifically in the case of hypothyroidism, weight gain. So, back to your great question: Is there any link between the two? TBH, we’re not entirely sure. While it has been found that women suffering from PCOS may have a higher risk of thyroid dysfunction, the exact reason behind this remains unknown. But because of the similarity in symptoms, providers will often check thyroid hormones when evaluating patients for PCOS, and vice versa.

Your thyroid while you’re preggers

During pregnancy, increasing demands from a developing baby can occasionally cause new onset or worsening hypothyroidism for mama. Additionally, impaired thyroid function prior to and during conception can impact healthy brain development in the fetus. What does this mean for you? While regular screening of thyroid levels prior to pregnancy or early in pregnancy is provider and practice-specific. This is because current national guidelines on universal screening are inconclusive. If you have a family history of thyroid dysfunction, a personal or familial history of autoimmune disease (which can be related to thyroid function), or are suffering from symptoms of hypothyroidism, ask your provider about testing your thyroid.

Currently, there is insufficient evidence to back regular screening for all pregnant patients. According to UptoDate, the current recommendations suggest screening only at-risk women who have symptoms of thyroid disease, a personal or family history of thyroid disease, or a personal history of infertility, obesity, or autoimmune disorders.

Let’s chat nutrition for a happy thyroid

Though some cases of thyroid dysfunction are out totally of our control, maintaining a healthy diet that contains vitamins and minerals to support your thyroid can be beneficial. Studies have shown that iodine, selenium, iron, vitamin A, and zinc are all crucial to keeping thyroid happy and healthy, for both pregnant and non-pregnant women alike. Eggs, prunes, and lima beans are rich in iodine, while brazil nuts, chicken, brown rice, sunflower seeds, mushrooms, oatmeal, spinach, and bananas are fantastic sources of selenium.

For hypothyroidism specifically, I recommend my patients stick to a low-calorie, low-salt diet with foods rich in iodine and antioxidants, as well as seafood. For those suffering from hyperthyroidism, an ideal diet contains foods that counteract thyroid hormone production, such as broccoli, cabbage, cauliflower, and radish. Due to an increase in metabolism in hyperthyroidism, it is also recommended to consume nutrient-dense foods and avoid any low-calorie diets.

So, what’s the bottom line with all this? Well, for starters, even though the thyroid is a tiny little gland, it’s pretty important. Because it isn’t checked regularly, being aware of the symptoms of thyroid imbalance is incredibly useful. If your periods are irregular or you’re experiencing something unusual that resembles the above symptoms, pay a visit to your provider. They can help you get to the bottom of it — you’re not alone.

Last but not least: If all of this has got you wondering about your own thyroid levels, or your fertility as a whole, Modern Fertility’s got you covered. If you’re not on hormonal birth control, the hormone test kit includes thyroid testing (among other important hormones) to complete a few pieces of the fertility puzzle. Even teeny glands like the thyroid and short, three-letter acronyms can give you a big-picture perspective of your health — talk about powerful.

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Kara Earthman

Kara Earthman is a Women's Health Nurse Practitioner (WHNP) and writer living and working in Nashville, TN. You can find more of Kara's work on her blog EarthWoman.

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