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Thyroid & Fertility 101

The thyroid gland--- it’s been getting so much (well-deserved) attention in the past few years, especially in the fertility world.

Research clearly shows that having healthy thyroid function affects a woman’s ability to get pregnant and her ability to stay pregnant. Avoiding miscarriage is one of the most important reasons why you should know what your thyroid function looks like and have it be properly treated.

Let’s cover the basics:

The thyroid gland is a butterfly shaped bit of tissue in your throat, right in front of your vocal cords. It releases two hormones called Thyroxine (T4) and Tri-iodothyronine (T3). T4 is released into the bloodstream and it goes to every single cell in the body. Once it moves into a cell, T4 can be activated into Tri-iodothyronine (aka T3). While T4 does have an impact on our cells, T3 is what really does the magic. T3 binds to the DNA inside the cells and amplifies energy production, protein creation, and cell development.

When T4 and T3 aren’t in balance, women can have symptoms in any system of their body.

  • Fatigue

  • Depression

  • Difficulty with weight management

  • Feeling cold all the time

  • Constipation

  • Bloating

  • Itchy, dry, flaky skin

  • Irregular or heavy periods

  • Infertility

  • Recurrent Miscarriage

  • Muscle aches or soreness

  • High cholesterol

How does the thyroid know how much T4 and T3 to release? With Thyroid-Stimulating Hormone (TSH) from the brain, specifically the pituitary. Your brain is constantly testing your blood to get a sense of how much T4 and T3 is swimming around. Much like the thermostat in your home, if the T4 & T3 levels are too low, the brain will make more TSH to ask the thyroid gland to make more. If there’s too much T4 and T3, the brain makes less TSH.

When we are talking about fertility, research tells us that having a TSH between 1.0 and 2.51 means the thyroid will produce healthy levels of T4 and T3 and the uterus and ovaries will have all the right information to allow a woman to get and stay pregnant. In the general population, conventional medicine says a TSH of up to 4.5 is normal. In our practice, no matter her age, we want our patient’s thyroid working optimally so we always aim to see the TSH in the 1-2.5 range.

For the sake of fertility, we have to remember the hormone system in the body is like a big spider web. If one hormone is off-balance, it’s going to affect all the other hormones in the body. When thyroid function is imbalanced, the message to the ovaries about when to release an egg (ovulation) gets mixed up. The uterus also can get mixed messages about how thick of a lining to grow. Then there are all the other effects of low thyroid, including depression, weight gain, constantly feeling cold, exhaustion, constipation, dry skin and hair loss.

Given that nearly 20 million people in America have hypothyroidism2 (meaning their TSH > 4.5), we screen all our fertility and hormone patients for thyroid imbalance. We couldn’t count how many women in our practice who have been told their thyroid is “fine” even though their TSH was higher than 2.5 and they have all the classic symptoms of hypothyroidism. We believe in taking a comprehensive view of thyroid function and we will walk you through our evaluation process, to make sure the thyroid isn’t an obstacle to pregnancy.

Did you get tested for thyroid imbalance when you talked to your doctor about your fertility issues? Did they order a comprehensive panel and walk you through all the results so you understood what was happening in your body?

If you’re looking for a thorough, proactive approach to understanding your thyroid & hormone balance, schedule a call with us to see how we can work with you!

Are you ready to kick off your fertility journey?

1. Subclinical hypothyroidism in nonpregnant adults - UpToDate. Accessed April 16, 2019.

2. Diagnosis of and screening for hypothyroidism in nonpregnant adults - UpToDate. Accessed April 16, 2019.

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