How are thyroid disorders?
Your thyroid gland is the butterfly-shaped organ in the front of your neck that produces hormones that regulate your body’s metabolism and affect vital functions. Fertility refers to a couple’s ability to conceive and bring a baby to term. The relationship between your thyroid health and fertility is an important and sometimes complex part of conception.
Thyroid disorders refer to a group of disorders that cause dysregulated functioning of the thyroid gland, resulting in the overproduction (hyperthyroidism) or underproduction (hypothyroidism) of thyroid hormones, triiodothyronine (T3), and thyroxine (T4).
The most common hypothyroid disorder is the autoimmune condition, Hashimoto’s thyroiditis, which is predominant in women. Graves’ disease, another autoimmune condition, is the most common cause of hyperthyroidism.
The Connection Between Thyroid Disorders and Fertility
Estrogen tends to get all the attention, but balanced thyroid hormones are equally important for conception
What are the risk factors for hypothyroidism?
- Women are at increased risk of an under active thyroid during or after pregnancy if they are over age 30 or have:
- Past infertility or preterm delivery
- A family history of thyroid or autoimmune disease
- Type 1 diabetes or other autoimmune disease
- Prior radiation treatment of the head or neck
- Past thyroid surgery
- Thyroid antibodies, mainly thyroid peroxidase (TPO) antibodies, which are often present in Hashimoto’s disease
- A goiter (enlargement of the thyroid gland)
- Current treatment with levothyroxine, a thyroid hormone drug, unless the dose is adjusted before or soon after conception
How can thyroid disorders effect your fertility?
Hypothyroidism and hyperthyroidism can each negatively impact fertility—both the ability to become pregnant and the ability to carry a fetus to term. The presence of autoimmune antibodies, with or without hyper or hypothyroidism, can also impact your fertility.
Dr. Elena Christofides MD, FACE, and Fellow of the American Association of Clinical Endocrinologists, explains that “abnormal TSH levels can interfere with ovulation,” and that, “when you have any type of thyroid disorder (without proper management), you will see a luteal phase (the last half of the cycle after ovulation) disruption.”
This is mediated by progesterone levels. If a thyroid disorder is unregulated, a patient could have difficulty getting pregnant because there will not be implantation. You could also experience early miscarriage because of incomplete implantation.
Signs of low levels or misfunctioning of progesterone include:
A shorter or longer cycle than your typical menstrual cycle
Lighter or heavier bleeding than is typical for you
Longer or shorter windows for bleeding than is typical for you
Fertility is not a female-only concern. Thyroid disorders in men can also affect a couple’s fertility. Dysregulated thyroid function can damage sperm quality and motility, making it difficult for the sperm to enter the egg for implantation.
Hypothyroidism and Fertility
Too little thyroid hormone can impact fertility in the following ways:
- Disruption of the menstrual cycle, making it harder to conceive.
- Interference with the release of an egg from the ovaries (ovulation)
- Increased risk of miscarriage
- Increased risk of premature birth
The link between autoimmunity, inflammation and fertility
Autoimmunity can negatively affect fertility, even when TSH levels are within normal range. Dr. Unuane explains that the immune imbalance indicated by thyroid antibodies can impact fertility by:
- Causing difficulty with fertilization of the egg
- Causing difficulty with implantation
- Increasing the risk for miscarriage
Specialists don’t always agree on whether or not your antibody count is an important factor. Dr. Christofides explains that while the antibody count does not matter for diagnosis (the presence of any level of thyroid antibodies indicates an autoimmune condition) the antibody count can be clinically significant.
Because both the presence of antibodies and thyroid hormone levels play an important role in fertility, it is important to work with your doctor to achieve a stable balance, based on your individual needs.
References
https://www.hormone.org/diseases-and-conditions/pregnancy-and-thyroid-disease/hypothyroidism-and-pregnancy
https://www.mayoclinic.org/diseases-conditions/female-infertility/expert-answers/hypothyroidism-and-infertility/faq-20058311#:~:text=With%20hypothyroidism%2C%20your%20thyroid%20gland,ovulation)%2C%20which%20impairs%20fertility.
