pregnancy, infertility, thyroid, hyperthyroidism, hypothyroidism

Your thyroid is a little gland in the front of your neck, just below your larynx or "voice box". The thyroid gland is one of the "endocrine glands", and it makes hormones to regulate physiological functions in your body.

The thyroid gland manufactures thyroid hormones, which regulate the rate at which your body carries on its necessary functions. Other endocrine glands are the pancreas, the pituitary, the adrenal glands, the parathyroid glands, the testes, and the ovaries.

Diseases of the thyroid gland, especially when you are pregnant or trying to get pregnant are very common and affect millions of Americans. Having an underactive thyroid level increases your risk of having a miscarriage.

How are thyroid diseases diagnosed?

The first step in diagnosing thyroid disease is to get a good history and examination. However, the actual diagnosis of thyroid disease is based on laboratory tests, usually the TSH test, because many of the usual thyroid symptoms such as fatigue, weight change, heat intolerance, constipation, and menstrual irregularities are also seen among individuals who do not have thyroid disease. 

What happens during a thyroid disease examination?

  • Feel the neck
  • Listen by stethoscope to the thyroid gland
  • Tests reflexes
  • Check blood pressure, heart rate, and rhythm
  • Measure your height and weight, and calculate the BMI body mass index
  • Examine the face, eyes, nose, skin, nails, hands

Clinical signs of thyroid disease

  • Over/underweight
  • Intolerance to cold
  • Intolerance to warmth

Common symptoms of hypothyroidism and hyperthyroidism:

Hypothyroid Hyperthyroid
  • Constipation
  • Slower thinking
  • Weight gain
  • Fatigue
  • Lack of energy
  • Heavy menstrual periods


  • Loose bowel movements
  • Jitteriness, shaking
  • Weight loss
  • Feeling hot
  • Fatigue
  • Shorter/Lighter menstrual periods

Thyroid disease tests

  • TSH - Thyroid Stimulating Hormone) [should be below 2.5-3 mU/L, but depends on individual parameters]
  • Anti-thyroid Microsomal Antibody Testing
  • Total T4/ Total Thyroxine
  • Free T4 / Free Thyroxine
  • Total T3 / Total Triiodothyronine
  • Free T3 / Free Triiodothyronine
  • Thyroglobulin/Thyroid Binding Globulin/TBG
  • T3 Resin Uptake (T3RU)
  • Reverse T3
  • Thyroid Peroxidase Antibodies (TPOAb) / Antithyroid Peroxidase Antibodies
  • Antithyroid Microsomal Antibodies / Antimicrosomal Antibodies
  • Thyroglobulin Antibodies / Antithyroglobulin Antibodies
  • Thyroid Receptor Antibodies (TRAb)
  • Thyroid-Stimulating Immunoglobulins (TSI)

Imaging tests

  • MRI or CT Scan
  • Thyroid Ultrasound
  • Nuclear Scan/Radioactive Iodine Uptake (RAI-U)

What are the different types of thyroid diseases?

  • Hyperthyroidism: An overactive gland that produces too much thyroid hormone
  • Hypothyroidism: An underactive gland that doesn't produce enough thyroid hormone
  • Hashimoto’s Disease: An autoimmune disease that causes hypothyroidism
  • Graves’ Disease: An autoimmune disease that causes hyperthyroidism
  • Goiter
  • Nodules
  • Thyroid Cancer

An enlarged thyroid gland is often called a "goiter." Sometimes inflammation of the thyroid gland can cause enlargement of the gland.

An abnormal thyroid function before and during pregnancy (either too much or too little hormone) can have a major effect both on your fertility and the developing baby. It's best to diagnose and treat thyroid problems before pregnancy to improve both your fertility and your chance for a good pregnancy outcome. Being diagnosed and treated can significantly enhance your chances of having a healthy baby.

Hypothyroidism and fertility

If your periods are irregular and you have trouble conceiving, hypothyroidism could be the cause of the fertility problem. If you get pregnant anyway, hypothyroidism increases your risk of miscarriage, and the baby could also have problems.

Hypothyroidism is a condition in which the body lacks sufficient thyroid hormone. As many as one in 10 women have some form of hypothyroidism before or during pregnancy, though most don't realize they have it. Often, the symptoms associated with hypothyroidism (especially in early thyroid disease) can be difficult to differentiate from typical pregnancy tiredness and exhaustion.

The classic symptoms of hypothyroidism are:

  • Lethargy, fatigue, weakness
  • Weight gain or increased difficulty losing weight
  • Dry skin
  • Hair loss
  • Cold intolerance
  • Constipation
  • Depression
  • Decreased libido
  • Reduced heart rate
  • Development of goiter

Instead, when you have an abnormal thyroid function during pregnancy you may experience more subtle ones such as weight gain, skin problems, abnormal menstrual cycles (irregularity, heavy periods, loss of periods, or dysfunctional uterine bleeding).

Because some symptoms of hypothyroidism, such as tiredness and weight gain are already quite common in pregnant women, doctors often overlook it as a possible cause of these symptoms.

Babies born to mothers with untreated hypothyroidism during pregnancy have been found to have lower IQs. That's why some doctors suggest that all pregnant women and those planning to become get pregnant should be routinely tested for hypothyroidism.

In many cases, no specific cause can be found. Thyroid illness may follow an infection of the thyroid or an autoimmune condition, such as Hashimoto's disease, or it could result from surgical removal of part, or all, of the thyroid.

Treatment for hypothyroidism during pregnancy consists of daily taking a daily synthetic thyroid hormone, and continuing to take it throughout pregnancy. It usually takes about eight weeks for thyroid function to return to normal on the medication, and the dosage may need adjusting in the first few weeks/months. With proper dosage, there are no side effects to mom or baby. Women with previously treated hypothyroidism may have to increase their dose of medication during pregnancy. 

Read More:
Taking Thyroid Medication During Pregnancy
Thyroid to Blame for Some Pregnancy Complications
Thyroid Stimulating Hormone (TSH) During Pregnancy