Assessing Thyroid Health Prior To Pregnancy

This topic speaks to me since working on my thyroid health has been my main priority when preparing for pregnancy. When I got off the pill over 10 years ago, the biggest area that took a hit was my thyroid. It’s been something I’ve struggled on and off with over the last ten years. You probably wonder why I struggle if I know how to support my thyroid, and the truth is because life happens to everyone. Finishing school, entering the workforce, getting married, starting a business, and moving all over the country for the military built up a lot of stress. Certain times were more stressful than others, and that is when I would see thyroid issues arise. This last year had a lot of uncertainty with my husband’s job, where we would live, and many changes in my business. I completely burnt myself with 1:1 clients over the last four years, and while I ate well, was smart with exercise, and took my supplements, you can’t hide from stress. When we decided we wanted to try to conceive soon, it forced me to take a deeper look at my thyroid health and stress. Why is thyroid health such a big deal when it comes to getting pregnant? That’s what our focus is in this blog.

Thyroid and Fertility Connection

There are a few ways that a poorly functioning thyroid can contribute to difficulties with fertility and conception.

  1. Delays ovulation: lack of adequate thyroid hormone can prevent ovulation or delay it. We have to ovulate in order to release the egg from our ovaries and then conceive.
  2. Lower progesterone: we only make progesterone when we ovulate.
  3. Can lead to higher insulin and androgen (male hormone) levels.

One eyeopening study shows how suboptimal thyroid health can impact fertility and conception here:

“A study showed that women who never achieved basal TSH <2.5 mIU/l or Thyrotropin releasing hormone-stimulated TSH <20 mIU/l had lower conception rates.[4] Women with TSH ≥2.5 mIU/l have significantly higher BMI, fasting insulin concentrations, total testosterone and free androgen indices and decreased sex hormone–binding globulin concentrations.”

Recurrent miscarriages and pregnancy complications have also been shown to be impacted by thyroid function:

“Pregnant women with subclinical hypothyroidism or thyroid antibodies have an increased risk of complications, especially pre-eclampsia, perinatal mortality, and miscarriage. Universal screening for thyroid hormone abnormalities is not routinely recommended at present, but thyroid function must be examined in female with fetal loss or menstrual disturbances. Practitioners providing health care for women should be alert to thyroid disorders as an underlying etiology for recurrent pregnancy loss.”

Thyroid health is essential for fertility, conception, and health during pregnancy and postpartum.

Assessing Thyroid Health

There are a number of ways to assess your thyroid health:

  • Symptoms
  • Basal Body Temperature
  • Blood Labs
  • Hair Mineral Testing

Symptoms of Suboptimal Thyroid

I don’t recommend going solely based on symptoms when it comes to thyroid function, but it is helpful to monitor these and compare them to your other markers and labs.

  • Low body temp (see below)
  • Low pulse
  • Hair loss/texture changes
  • Irregular cycles
  • Depression
  • Anxiety
  • Brain fog
  • Poor memory
  • Fatigue
  • Feeling cold frequently
  • Constipation
  • Dry Skin
  • Acne
  • Unexplained weight gain
  • Difficulty losing weight

Basal Body Temperature (BBT)

Basal body temperature (BBT) is your temperature at rest. Measuring your BBT first thing in the morning before you get out of bed keeps it from being impacted by digestion, stress, movement, etc. You can use any thermometer to measure BBT, however, a basal body thermometer gives a more accurate reading because it goes to the 100th degree (98.45°F vs. 98.4°F). Menstruating women’s body temperature will increase during the second half of their cycle after ovulation occurs and will be lowest during the 2nd and 3rd day of your period (typically). So, what should your BBT be? Ideally, on average, you want the first half of your cycle to be 97.6°F and the second half to be 98.4°F. When your body temperature is below this, it is a sign of less heat being produced AKA sluggish thyroid. This simple measurement can be used daily to monitor thyroid and hormone health.

Why I always recommend looking at BBT even if thyroid labs are normal:

During his research in med school, Dr. Broda Barnes found thyroid testing to be wildly inaccurate. In the past, thyroid function testing consisted of measuring basal metabolism at rest through oxygen uptake. It was later discovered that T4 could be measured followed by T3. The problem with that is it only shows up in more severe cases of thyroid dysfunction. For this reason, patients who clearly showed signs of thyroid dysfunction did not qualify for medical diagnosis. Dr. Barnes discovered that measuring the body’s temperature at rest is a great measurement of thyroid function, instead of relying on oxygen tests, which were very impractical, expensive, and inaccurate.

Thyroid Blood Labs

Blood work is the traditional way to look at thyroid health. While I think it can be helpful, it’s important to look beyond this with tools like hair mineral testing and BBT. I have seen so many women (and I’ve been there myself) that have “normal” thyroid labs, but have all the symptoms of hypothyroidism, struggle with their hormones, and have low body temperatures.

What blood work is the most important when it comes to the thyroid?

  • TSH: thyroid stimulating hormone–made by your pituitary gland and tells your thyroid it needs to make more thyroid hormone
    • optimal is .5-2 (<2.5 during pregnancy)
  • Free T4: inactive form of thyroid hormone–shows us how much thyroid hormone your thyroid is producing
    • optimal is 1.4-1.8
  • Free T3: active thyroid hormone–shows us how much thyroid hormone is being converted
    • optimal is 3.5 and higher
  • Reverse T3: puts the breaks on thyroid hormone conversion–indicates stress
    • optimal is less than 15
  • Thyroid antibodies: indicate if autoimmune condition is present
    • goal is negative

An important note on thyroid labs and pregnancy. Optimal TSH levels are lower during pregnancy (ideally 2.5 or less). We need adequate thyroid hormone for the baby’s neural development. Iodine deficiency can also cause hypothyroidism as well as Hashimoto’s. Here’s an excerpt from a research article explaining how it impacts fetal development:

“The impact of severe iodine deficiency or congenital hypothyroidism on the fetus and newborn is profound, as are the effects of overt maternal hypothyroidism on pregnancy. The severity, timing of onset and duration, as well as postnatal management, all influence fetal and neonatal brain development. It is now believed than even mild maternal hypothyroidism (from mild iodine deficiency, thyroid autoimmunity, or thyroid under-replacement) may affect fetal brain development.”

Hair Mineral Testing

Another way to assess thyroid health is via mineral status. There is a thyroid mineral ratio on the hair mineral test, but there are also a number of other minerals that impact how our thyroid functions which I list below but you can also learn more about the thyroid-mineral connection here.

  • Calcium
  • Potassium
  • Thyroid ratio (Ca/K)
  • Magnesium
  • Selenium
  • Copper
  • Zinc
  • Iron
  • Heavy metal levels

Calcium & Potassium on HTMA

Calcium: High levels of calcium bind to iodine receptors and make it difficult for thyroid hormone to bind

Potassium: Helps to sensitize cells to thyroid hormone and get thyroid hormone inside the cell where it does its job

Other Essential Minerals For Thyroid Function

  • Copper stimulates the production of the thyroxine hormone T4 and helps to maintain optimal thyroid function by supporting energy production in the body. Copper also regulates iron, which is important for thyroid hormone conversion.
  • Magnesium protects against oxidative stress and inflammation which damages the thyroid gland. Essential for making ATP that powers the sodium-iodide symporter to transport iodine into thyroid cells.
  • Selenium helps initiate the creation of thyroid hormones, activates thyroid hormones, and helps to convert T4 to T3. It also helps to support the recycling of iodide to make more thyroid hormone and protects against damage by reducing oxidative stress and heavy metal contamination.
  • Sodium transports iodide into thyroid cells in order to make thyroid hormones via the sodium-iodide symporter. Also supports insulin sensitivity, which can impact micronutrient status and thyroid function.

You can complete a hair mineral test through my course, Master Your Minerals. The course allows you to order a test when you purchase or in the future inside the course. You can also apply to work 1:1 with our team if you are looking for more personalized help in navigating your thyroid and hormone health.

Thyroid Health Postpartum

One of the reasons I am so passionate about women understanding their thyroid health before pregnancy is how it can impact you after you have your baby. I can’t tell you how many women I’ve seen struggle with postpartum anxiety and depression only to be given medication rather than have any investigation on their hormones and thyroid health. Then when we do address thyroid health, their symptoms drastically improve, and they begin to feel like themselves again.

The Connection Between Thyroid Health & Depression

Our cells all have a little engine that takes the nutrients from the food we eat and turns them into energy (ATP) and disperse this energy throughout the body. When we don’t eat enough food, we don’t make enough energy. Another important aspect of this energy production is thyroid hormone. Our thyroid helps dictate how much energy the engines in those cells will produce. Adequate levels of thyroid hormone and its ability to get inside the cells allows our cells to use more oxygen and generate more energy and heat for the rest of the body. Without adequate thyroid hormone our cells won’t produce enough energy.

This lack of energy shows up in the body in a number of ways:

  • lower body temperature–cold hands and feet, feeling cold often
  • low mood
  • slower cognitive function
  • low progesterone
  • low testosterone
  • high estrogen
  • acne
  • anxiety
  • depression

There are a number of research articles that dig into the connection more. A few interesting connections between thyroid hormone production and depressive symptoms:

  • participants with low T4 hormone production (inactive form of thyroid hormone) had depressive symptoms
  • participants with normal T4 but low T3 (the active form of thyroid hormone–the body has to conver it) also had depressive symptoms
  • participants with normal but not optimal levels of both T4 and T3 experienced depressive symptoms
  • patients with depression and no other illnesses all had low levels of T3 (active form of thyroid hormone)

This shows a couple things:

  1. There is a clear connection between low thyroid hormone levels and depression, but you can also have suboptimal levels and experience depression.
  2. Thyroid function isn’t always as simple as low hormone levels. It’s also about how our bodies are using that thyroid hormone. Calcium and potassium levels are very important for this. This is why I do hair mineral testing with all of my clients.

Want to nerd out? Here are some helpful articles:

There is also my free thyroid-mineral connection webinar that will help you continue learning about your thyroid health.

reminder: i’m currently taking on 1:1 clients. if you’d like to explore what it would be like to work together and if we are a good fit, fill out this form to get more details!​

Amanda Montalvo

Amanda Montalvo is a women's health dietitian who helps women find the root cause of hormone imbalances and regain healthy menstrual cycles.

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