How Your Thyroid Can be Affecting Your Fertility

Thyroid DysFUNKction, (not in a good 80's rap funk type way, as in funky, bottom of the school lunch box type funk) which can really be affecting your fertility. If you have been trying to have a baby for some time, and have been unsuccessful, then it might be worth getting your thyroid function checked.. Before you embark on expensive medical procedures, it is well worth your while getting your preconception checks inclusive of a full thyroid picture. This is something we see in the Mums and Bubs clinic time and time again. Couple coming in who have been trying to conceive (TTC for those in the know) for a lengthy period of time, who haven't even been guided in that direction. Thyroid function is pivotal for fertility and healthy pregnancy, surprisingly there are alarming rates of men and women have thyroid dysfunction. 

Being in the field of preconception and family planning, we are often quite surprised that some doctors and specialists rarely include comprehensive thyroid testing as part of a preconception assessment. When I say comprehensive, I mean the whole picture, not just ONE marker in a blood test, I believe the entire symptom picture inclusive of full bloods, full case history, basal body temperature charting, the works is a much needed focus in getting you and your partner baby ready!. The thyroid is is so complex and there are very technical reasons why just one marker in a blood test isn't enough in this day and age, and subclinical hypothyroidism is often overlooked, until... well there are problems obtaining that pregnancy and sadly can result in miscarriage if overlooked. 

There are many many reasons for infertility and this is a huge player. It's easy to assess with your health care practitioner, and we at the M&B clinic can easily and effectively monitor your thyroid function, or even see if this is potentially something that may be the "missing link".The good news is that most of the subclinical thyroid problems can be reversible.

What Factors Impact Thyroid Health?

  • Genetic susceptibility
  • High levels of stress
  • Nutrient deficiencies
  • Autoimmune disorders
  • Infections
  • Other hormone imbalances e.g. oestrogen dominance, high prolactin levels
  • Exposure to environmental toxins – radiation, chemicals, pesticides, heavy metals e.g. mercury & fluoride


A More Detailed Look at How Thyroid Health Affect Couples TTC.

Poor thyroid function or thyroid dysfunction upsets your body’s natural balance of reproductive hormones and has been found that 25% of female infertility cases and 15% of menstrual cycle disorders result from thyroid dysfunction. Subclinical (not diagnosed thyroid disease) is actually huge amongst the female population, and i believe is a massive call for thorough examination, when patients present with infertility or miscarriages. So lets have a quick look at how the thyroid may present if it is not functioning. 

Anovulatory cycles   

This means that you are not ovulating i.e. not releasing an egg.  Luteinizing Hormone (LH) has the task of stimulating the ovary to release the egg.  If thyroid hormone levels are not ideal they cannot support LH to do this.  If no egg is released this well....makes pregnancy impossible. It is still possible to menstruate regularly but not ovulate so you may not be aware of this.

Luteal Phase Problems 

so, It takes 13-15 days to nurture a fertilized egg. If the second half of your menstrual cycle (luteal phase) is too short due to poor LH response and subsequent insufficient progesterone production (T3 required for progesterone release from the luteal cells), a fertilized egg can’t implant securely and will end up leaving your body at the same time that menstruation would occur. This very early miscarriage is often mistaken as a regular period, and is sadly very very common in patients with subclinical hypothyroidism.

Low Body Temperature 

Low thyroid function will also result in a lower basal body temperature.  The rapidly dividing cells in a little embryo require a specific temperature range for that division to take place.  If your basal body temperature is too low, the embryo may be unable to continue to grow.  This increases the risk of early miscarriage.

High Prolactin Levels  

Elevated levels of Thyroid Releasing Hormone (TRH) and low levels of Thyroxine (T4) can also result in an excess of prolactin (normally produced by the pituitary gland to promote lactation) and TSH both of which will have a negative effect on fertility and can prevent ovulation or result in irregular or absent periods.

Other Hormonal Imbalances   

Reduced sex hormone binding globulin (SHBG), oestrogen dominance, progesterone deficiency, all interfere with proper reproductive hormone balance.  Oestrogen is a known antagonist to thyroid hormones so oestrogen dominance can suppress thyroid function.  Balanced oestrogen and progesterone levels will facilitate normal thyroid function and vice versa.

Loss of libido 

Sex drive is influenced by a number of physical and emotional factors.  Hormones can have a powerful effect on sexual desire.  When other hormone imbalances are combined with the fatiue and mood changes associated with a thyroid disorder it really can dampen libido.

Pregnancy risks

Undiagnosed and untreated thyroid problems can endanger your pregnancy and worsen pregnancy problems such as fatigue, hair loss, depression, morning sickness, preterm labour, inter uterine growth retardation, and increased risk of miscarriage.

Risks for your baby

Poor thyroid function may also put your baby at risk of a preterm birth and low birth weight.  There is also the risk of thyroid problems, impaired growth and development of the testes in male babies and possible problems with fertility as an adult.  Where severe iodine (a major component of thyroid hormone) deficiency is part of the picture, there is increased risk of cognitive problems and brain development in the baby. The Australian Thyroid Foundation also recommends you speak to your doctor about the importance of testing and monitoring your thyroid hormone levels. A healthy Thyroid hormone level is essential for the development of the foetus and sustaining pregnancy.l The latest research stated, ADHD and Autism can be aresult of iodine deficiency and low thyroid hormone level in a pregnant woman. 



1. Do you have any of the common signs & symptoms associated with low thyroid function?

  • Inability to conceive (12+ months)
  • Miscarriage
  • Menstrual irregularities
  • Period pain
  • Low libido
  • Lethargy & fatigue
  • Susceptibility to the cold / cold hands & feet
  • Inability to lose weight
  • Changes in texture of skin, nails, hair, hair loss
  • Recurrent infections
  • Constipation

BBT? what is this?

Basal Body Temperature, this is something in the clinic we take pretty seriously for couples trying to conceive, or assessing ovulation and thyroid status. checking your BBT is a very non invasive way to check for potential thyroid dysfunction.  Often, routine blood tests may appear “normal” because the problem is occurring in the cells and not in the blood.  If your thyroid function is optimal, your temperature will be between 36° and 37° C but ideally above 36.5°C, if it is below this, then time to come in and have a chat to us :)

Blood Test Jibba Jabba

For full thyroid assessment you require readings for TSH, T4, T3, rT3 & Thyroid Antibodies.  TRH may also be required.  At the Mums and Bubs clinic when assessing your fertility, ideally, your Thyroid Stimulating Hormone (TSH) level should be between 0.9 and 2 mIU/L, Thyroxine (T4) between 16-20 pmol/L, Triiodiothyronine (T3) between 4.5 – 6.0 pmol/L, reverse T3 below 250 pmol/L and 0 IU/ml for thyroid antibodies.  Your doctor or naturopath can order these tests and assess the results for you. looking at these figures, some of you may notice that the levels all appear to be well within the range, yes that is true, as natural health care practitioners, we believe these results are ideal, and outside of these results can sometimes be indicative of subclinical hypothyroidism/hyperthyroidism. Speaking to doctors, they often agree with us that, it is only when outside these markers they treat with medication, but we like to address issues before they become a "disease". This is also why we don't rely on just looking at the TSH levels in a test, as this does not give us a the entire thyroid picture. 

4.  Urinary Iodine                                                                                                                              

Iodine is a key component of thyroid hormone.  Excessive iodine as well as a deficiency of iodine can result in low thyroid function.  Urinary iodine should ideally be between 150-200ug/L.  At Mums and Bubs we can also order and decipher this test for you.

5.  Diet & Lifestyle                                                                                                                               

-Our modern western diet is a major contributor to increasing thyroid health problems.  Foods detrimental to thyroid health include refined grains, simple sugars, soy products, peanuts & peanut products, caffeine, hydrogenated oils, cigarette smoking and alcohol.  Excessive consumption of uncooked vegetables such as cabbage, broccoli, turnips, Brussels sprouts may block the absorption of iodine, again everything in moderation and we at mums and bubs can assess and look at your diet to see if there is anything in excess or lacking that may be messing with your jam.

- Exposure to heavy metals e.g. mercury (amalgam fillings) and fluoride (water supply, toothpaste) as well as bisphenols in plastics may also be detrimental to the old thyroid.

-Stress management is absolutely imperative, and when trying to have a baby this is easier said that done. (Trust me, i have been there).  Stress results in elevated levels of cortisol, the main hormone released by the adrenal glands.  Increased cortisol will inhibit the conversion of T4 to the active T3 hormone and will stop the active T3 entering cells sufficiently.

-Exercise is beneficial as it will stimulate thyroid hormone secretion and increases tissue sensitivity to thyroid hormones.

So, take from this what you need and if you have any questions, don't hesitate to ask us or your health care provider.