What is your thyroid, what does it do, and how is thyroid dysfunction related to fertility? 

Thyroid 101:

The thyroid is a small butterfly-shaped gland located in the front of your neck. A key player in the endocrine system, its job is to produce and regulate hormones that control your body’s metabolism and vital body functions including breathing, heart rate and body temperature. It works in response to the pituitary gland, located in your brain. The pituitary gland communicates to the thyroid by creating thyroid stimulating hormone (TSH), which then stimulates the thyroid to produce other hormones – triiodothyronine (T3), thyroxine (T4).  

When T3 and T4 production is too high or low, it can cause weight and mood changes. An imbalance can also impact your menstrual cycle and fertility, causing irregular periods, ovulatory disorders, increased rate of pregnancy loss, preeclampsia, and preterm birth. If you are trying to conceive, your thyroid health is something to think about! 

Thyroid disorders most commonly associated with fertility:

The thyroid gland is essential to growth and development and thus plays an important role in reproduction. It is regulated by the hypothalamus-pituitary axis (HPA), which is the connection and feedback loop between the hypothalamus (a part of the brain that produces hormones) and the pituitary gland (which waits for signals from the hypothalamus). When one sends a signal, it sets off a chain reaction in the other. The HPA controls the production of some of the most important hormones related to fertility, thus thyroid dysfunction can influence how much of these hormones are released. When hormone levels are off, it can disrupt menstrual cycles. And without a healthy cycle (building of uterine blood lining, ovulation, fertilization, and implantation), conceiving becomes a challenge. 

The thyroid can malfunction most commonly in two ways:

1. Hyperthyroidism – Overproduction of thyroid hormones due to an overactive thyroid. Found in up to 5% of women. Common symptoms include:
   • Anxiety
   • Tremors
   • Rapid heart rate
   • Brittle hair
   • Increased appetiteUnexplained weight loss
   • More frequent bowel movements
   • Intolerance to heat 
   • Infertility symptoms can include diminished libido and menstrual cycle irregularities. In pregnancy, hyperthyroidism can lead to pregnancy complications, such as a increased blood pressure late into the pregnancy, premature delivery, low birth weight, or even miscarriage.
     
2. Hypothyroidism – Underproduction of thyroid hormones do to an underactive thyroid. Found in 2-4% of women. Common symptoms include:
   • Fatigue, low energy 
   • Muscle weakness
   • Weight gain
   • Depression
   • Constipation
   • Intolerance to cold
   • dry skin
   • Infertility symptoms can include menstrual cycle abnormalities with cycles being heavier and less frequent, a low basal body temperature, lack of ovulation in some cases, and difficulty conceiving.
     
3. Hashimoto’s Thyroiditis – an autoimmune condition, where your immune system makes antibodies (TPO and TG antibodies) that attack the thyroid gland, often leading to hypothyroidism. Hashimoto’s thyroiditis affects more men than women, and it’s estimated that 4 in 10 women struggling with conceiving may have subclinical hypothyroidism (an early, mild form of hypothyroidism). For women, being diagnosed with Hashimoto’s doubles the risk of fertility problems. For men, an underactive thyroid can reduce sperm motility, cause abnormal sperm morphology, and lower testosterone and other sex hormones.

Diagnosis and Treatment:

The American Thyroid Association recommends routine thyroid screening for women starting at age 35. 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 have noticed symptoms of hypothyroidism or hyperthyroidism, it’s important to get your thyroid tested. A complete thyroid panel should test for your levels of TSH, T3, T4, free T4 in addition to TPO and TG antibodies.

There are a number of medications and treatment options to help improve thyroid function. If you’re trying to get pregnant now or in the future, here are some considerations: 

• TSH should optimally be below 2.5mlU/L.
• Vitamin D level – 37.5–50.0 μg (1500–2000 iu).
• Get enough selenium – 200mcg per day
• If you have Hashimoto’s, lifestyle changes may help lower TPO and TG antibodies. An anti-inflammatory diet is key, while exercise can increase serotonin levels. 

Your thyroid plays a vital role in your reproductive health. Schedule an appointment, I will work with you to support your thyroid function, hormone balance, and fertility.