Female Infertility and Thyroid Health, the Connection


It has been known for a long time that female fertility is closely linked to low thyroid function. Even a slight underactive thyroid function could still affect fertility in women (1). The reason why thyroid function and infertility are linked is still unknown, until recently. A recent research shed some light on why the two dysfunctions are connected. But before we get to the nitty-gritty, let’s learn some background information.

What is the Thyroid Hormone?

Thyroid is a small butterfly-shaped gland located in the front of the neck just below the Adam’s apple. It is made of two halves called lobes. The function of the thyroid gland is to produce thyroid hormone (T4) and to do this; it will take Iodine and combine with amino acid Tyrosine to create T4 and T3. T4 will then get converted into T3. T3 is considered the ”active” form of the thyroid hormone because it is about four times more powerful than T4. Thyroid hormones are then released into the blood and circulate to enter organ cells that require the hormones.

When T4 and T3 are low, the pituitary gland, which is located at the centre of the brain, will release Thyroid Stimulating Hormone (TSH). TSH, as the name suggests, is a hormone which stimulates the thyroid gland to produce T4. Therefore, the higher TSH level is, the lower T4 and T3 level in the blood.

Thyroid hormone is a crucial hormone as it is being used by just about every organ of the body. The brain requires thyroid hormone to maintain concentration and retain short term memory while the skeletal system requires thyroid hormone to grow and maintain strong bone integrity. In short, the thyroid hormone is a big deal.

What does Thyroid hormone got to do with fertility?

As I explained before that Thyroid hormones are needed by every organ of the body, including the ovaries. A 2016 research by the University of Pisa in Italy, shows that T4, T3 and TSH are presence in the fluid of ovarian follicles (2). Thyroid hormone receptors are also found in the luteinized granulosa cells in healthy fertile young women.

The research shows strong evidence that Thyroid hormones, as well as serum Iodine, are important factors in egg cells maturation in human female. The ovarian cell surface expresses enzymes that convert T4 into T3. In other words, the ovaries can convert T4 into T3 for their own needs independently, thus acting as a secondary ‘thyroid gland’. Furthermore, the small and growing ovarian follicles can take up iodine molecules circulating in the blood more than the matured ovarian follicles. This fact suggests the importance of serum Iodine in the maturation of human egg cells.

When it comes to female fertility, the importance of healthy functioning thyroid glands and an optimal level of blood iodine cannot be understated. And sadly, an often-overlooked factor in the treatment of female infertility.

How much Iodine do I need?

Australian Ministry of Health recommends 150 micrograms of daily Iodine intake for an adult and 1,000 micrograms (1 mg) as an upper-level intake to correct Iodine deficiency. Japanese culture has the highest Iodine intake in the world. A 2011 study found that Japanese population Iodine intake is averaging at 1,000-3,000 micrograms (1-3 mg) daily (3).

A recent survey of Australian population found; the average urban Australian iodine intake is 128 micrograms daily (4). This puts the average urban Australian iodine intake is less than the Australian government recommended daily intake. If you take the lowest Japanese iodine intake average of 1,000 micrograms and compare this to the average Australians, this put the Japanese iodine intake nearly eight-times higher than the average Australians.

With so many conflicting information, it gets very confusing for a lot of people. So how much iodine should we take daily? Taking too much iodine can be as damaging as iodine deficiency.

It is difficult to gauge how much iodine our body needs from day to day and whether we are deficient. There are tests to examine the serum iodine level, but these tests are expensive, their reliability is uncertain, and most doctors don’t even perform this test. Since we don’t know how much iodine we need and deficient of, taking iodine supplement internally can be tricky.

My suggestion is to take iodine topically using liquid iodine skin paint method, this way iodine will be absorbed through the skin and your body will take whatever amount iodine available on your skin and leave the rest.

To do this, using Lugol’s iodine paint about a palm-size iodine patch on your skin (inner arm, inner thigh, back of knees, back of elbows, neck, abdomen). Make sure you apply iodine paint skin patch on different part of your body every day.

Observe the iodine patch on your skin every hour. If the iodine patch disappears in less than 4 hours, this means you have a marked deficiency of iodine. If between 4-8 hours, you have a slight iodine deficiency. If the patch is still visible after 8 hours, you have an optimal level of serum iodine.

Iodine deficiency is just one factor in a long list of reasons behind thyroid disorder and infertility. There are so many contributing factors to infertility and the situation can be quite complex. If you are suffering from thyroid disorder and/or infertility, I recommend that you book an appointment with us at Green Heart Natural Health, a naturopathic clinic based in Inner West area of Sydney, Australia.


Iodine can be contraindicated in some thyroid autoimmune disease such as Hashimoto thyroiditis and many others. Please consult a healthcare practitioner before embarking on any health protocol.

Seaweed Recipe Idea:


Salad Seaweed Roll

Seaweed is a great source of dietary iodine. As most people in the West are deficient in iodine it is more important than ever to incorporate iodine rich seaweed into your everyday diet.