The thyroid gland has many roles and responsibilities in the body. A minor shift in optimal thyroid health can have significant effects on the entire body, including the ability to conceive and maintain a pregnancy.

When an otherwise healthy couple struggles to conceive, a simple adjustment to thyroid function can drastically improve fertility and pregnancy retention. It is important to get appropriate thyroid testing and evaluation as many times subclinical hypothyroidism, a condition in which the thyroid appears normal on lab work but the body functions as if the thyroid is unbalanced, is overlooked.

The thyroid gland is responsible for temperature regulation, metabolism, immune system function, and most importantly, fertility. It can affect ovulation, hormones that encourage implantation of a fertilized egg in the uterus, and estrogen and progesterone levels. A minimal change in thyroid levels can actually prevent an ovarian follicle from developing, leading to disruption in ovulation. A thyroid imbalance can also shorten the second half of a menstrual cycle, altering the time frame for a fertilized egg to properly implant in the uterus. This means if ovulation and fertilization do occur, the shortened cycle leads to uterine shedding before the egg properly implants.

The optimal estrogen/progesterone balance necessary for fertility and retention of a new pregnancy is highly sensitive to variations in thyroid hormone levels. Suboptimal thyroid hormone levels will negatively affect the estrogen/progesterone balance causing infertility or early miscarriages. A thorough evaluation of thyroid function is necessary if infertility occurs (defined as a pregnancy not occurring within 6 months of trying to conceive, or more than 2 consecutive miscarriages).

Typically, hypothyroidism is discovered long before a couple tries to conceive. The typical symptoms of fatigue, weight gain, irregular periods, and bowel disruption are present and testing/treatment for hypothyroidism begins. However, many women are unaware they have an imbalanced thyroid until they try to conceive unsuccessfully. A true diagnosis of hypothyroidism is primarily dependent on Thyroid Stimulating Hormone (TSH) levels between .5 – 4.5 on lab tests. However, clinical evidence and new research shows that fertility is negatively affected when the TSH is higher than 1.0 – 1.5 on lab tests and the active thyroid hormones T3 and T4 are on the outer limits of normal. Some women have a very small window of TSH levels on which the rest of their hormones depend for balance and proper function.

A study on subclinical hypothyroidism and infertility in 2012 showed that 23% of participants with infertility had a TSH over 2.0. When these particular participants were given thyroid medication, 76% of the women became pregnant within 6 weeks to 1 year.

For conception and prevention of miscarriage, it is extremely important to address thyroid health and to be sure TSH, T3, and T4 are within appropriate, if yet conservative, ranges on lab tests.

Subclinical hypothyroidism has many causes, including environmental toxin exposure, stress, gluten intolerance, nutritional deficiencies, and genetic predisposition. However, treatment for subclinical hypothyroidism – and subsequently infertility – can be simple and as studies show, quickly effective in resolving an underlying health issue.

Dr. Sinsheimer is a Naturopathic Doctor and can be reached at (760) 568.2598.

Sources: 1) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3657979; 2) http://www.pregnancy.com.au/resources/topics-of-interest/preconception/is-poor-thyroid-function-impacting-your-fertility.shtml; 3) http://natural-fertility-info.com/solve-thyroid-problems-before-conceiving-a-baby.html; 4) http://www.hotzehwc.com/en-US/Resource-Center/Articles/Infertility-Is-it-Low-Thyroid-in-Disuise.aspx; 5) http://www.sheknows.com/health-and-wellness/articles/807574/infertility-is-your-thyroid-to-blame