Thyroid disorders are conditions that affect the thyroid gland, a butterfly-shaped gland in the
front of the neck. The two main types of thyroid disease are hypothyroidism and
hyperthyroidism. Both conditions can be caused by other diseases that impact the way the
thyroid gland works. 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.
Thyroid disorders are the most common endocrine problems in women. In most cases,
the thyroid can lead to infertility or miscarriages. Hypothyroidism is more common among women
and can often be detected with a simple blood test of thyroid-stimulating hormone (TSH). Still,
many women remain undiagnosed, especially women with ill-defined, subclinical hypothyroidism.
Common symptoms of hypothyroidism include:
Frequent and heavy menstrual cycles
Dry skin and hair
Intolerance to cold
Hypothyroidism can impact fertility in the following ways:
- Disruption of the menstrual cycle, making it harder to conceive.
Thyroid dysfunction can affect fertility in various ways resulting in anovulatory
cycles, luteal phase defects, high prolactin (PRL) levels, and sex hormone imbalances. Many
infertile women with hypothyroidism had associated hyperprolactinemia due to increased
production of thyrotropin-releasing hormone (TRH) in ovulatory dysfunction. It has been
recommended that in the presence of raised PRL, the treatment should be first given to correct
the hypothyroidism before evaluating other causes of raised PRL. Measurement of TSH and PRL
is routinely done as a part of an infertility workup.
- Interference with the release of an egg from the ovaries (ovulation)
With hypothyroidism, your thyroid gland doesn’t produce enough of certain important
hormones. Low levels of thyroid hormone can interfere with the release of an egg from
your ovary (ovulation), which impairs fertility. Having low levels of thyroxine, or T4, or
elevated thyroid-releasing hormone (TRH) leads to high prolactin levels. This can cause
either no egg to release during ovulation or an irregular egg release and difficulty
conceiving. Hypothyroidism can also cause a shortened second half of the menstrual
- Increased risk of miscarriage
Prevalence of hypothyroidism in the reproductive age group is 2–4% and has been
shown to be the cause of infertility and habitual abortion. Even minimal hypothyroidism
can increase rates of miscarriage and fetal death and may also have adverse effects on
the later cognitive development of the offspring.
- Increased risk of premature birth
Thyroid hormone levels in the mother is very important in the growth and development
of the baby, especially early in pregnancy. Thyroid hormones are also important for the
normal development of the placenta, a critical component to maintaining pregnancy.
Research has shown that high thyroid hormone levels (hyperthyroidism) or low thyroid
hormones (hypothyroidism) are associated with poor outcomes for the mother and the
developing newborn. Pregnant women with mild thyroid dysfunction, such as subclinical
hypothyroidism, isolated hypothyroxinemia or thyroid peroxidase antibody positivity, are
more likely to deliver preterm when compared with euthyroid women.
Therefore, normal thyroid function is necessary for fertility, pregnancy, and to sustain a healthy
pregnancy, even in the earliest days after conception. A thyroid evaluation should be done on any
woman who wants to get pregnant with a family history of thyroid problems or irregular menstrual
cycle or had more than two miscarriages or is unable to conceive after 1 year of unprotected
intercourse. The comprehensive thyroid evaluation should include T 3, T 4, thyroid-stimulating
hormone (TSH), and thyroid autoimmune testing such as thyroid peroxidase (TPO) antibodies,
thyroglobulin/antithyroglobulin antibodies, and thyroid-stimulating immunoglobulin (TSI). Thyroid
autoimmune testing may or may not be included in the basic fertility workup because the
presence of thyroid antibodies doubles the risk of recurrent miscarriages in women with
otherwise normal thyroid function.
If you have any concerns about your thyroid function while pregnant or trying to become
pregnant, talk to a reproductive endocrinologist or an obstetrician/gynaecologist trained in fertility
and hypothyroidism. Call us at 8886592229 or visit https://bit.ly/3nHO7Ou and develop a plan
to ensure that your thyroid disease doesn’t interfere with a healthy pregnancy.
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