Can A “Lazy Thyroid” Cause Infertility?

The thyroid is a butterfly-shaped gland located at the base of the neck, in front, between the trachea and the esophagus. It produces two hormones, triiodothyronine (T3) and thyroxine (T4), which control many functions of the body: the metabolism of fats, carbohydrates, and proteins, the frequency of the heart and respiratory movements, the functioning of the gastrointestinal system and the assimilation of food, the production of red blood cells. They also control the regularity of the ovulatory cycle and female fertility: they are involved in the oocyte maturation and the preparation of the uterus to receive the fertilized oocyte at the beginning of pregnancy.

Hypothyroidism or “lazy thyroid,” i.e., insufficient production of the hormones T3 and T4, alters the functioning of all these systems. In particular, it causes menstrual cycle irregularities and reduces the likelihood of conceiving and becoming pregnant. The remedy is simple: it is sufficient to take levothyroxine daily, the synthetic substitute for the T4 hormone, to compensate for the lack of the natural one. It is up to the endocrinologist to diagnose hypothyroidism, prescribe treatment, and indicate the correct dosage of levothyroxine, which must be updated periodically based on the results of specific blood tests.

What Is Meant By “Sluggish Thyroid,” And How Do You Diagnose The Problem?

The most common cause of hypothyroidism is an autoimmune disease, Hashimoto’s thyroiditis. It is an immune system defect producing antibodies directed against the thyroid: the organism attacks itself by mistake. In the long run, these antibodies impair the functioning of the gland and the production of thyroid hormones. It is a widespread disease, more frequent in the female population than in men. It is estimated that 10% of women of childbearing age suffer from it.

Many are affected in asymptomatic form without knowing it: they are carriers of abnormal antibodies.

However, their thyroid is still functioning quite well, and the production of hormones is regular or slightly deficient. Over time the situation usually evolves, the production of hormones decreases, and the characteristic symptoms of hypothyroidism appear as chronic tiredness, heightened sensitivity to cold, difficulty concentrating, memory lapses, dry skin, and brittle hair. Anyone who experiences these symptoms should talk to their family doctor and schedule a visit with an endocrinologist specialist, who will prescribe the tests necessary to diagnose Hashimoto’s thyroiditis: the search for abnormal antibodies, the dosage of T3 and T4 hormones in the blood and thyroid stimulating hormone (TSH), the concentration of which has an inverse trend for that of T3 and T4, i.e., it increases the more the level of thyroid hormones is deficient.

Recent studies have shown that even a mild deficiency of thyroid hormones can hinder attempts to conceive, so even asymptomatic thyroiditis can reduce female fertility. For this reason, when a couple plans a pregnancy and has difficulty completing the project, the exams prescribed to the aspiring mother also include those to evaluate thyroid function, regardless of whether she shows suspicious symptoms.

What Happens In Pregnancy If You Have Untreated Hypothyroidism?

In addition to the risk of infertility, planning a pregnancy in a state of thyroid hormone deficiency brings other problems. If the conception is successful and the expectant mother is hypothyroid but does not know it, therefore, does not take levothyroxine to compensate for the defect, the probability increases that she will encounter some obstetric complications: spontaneous termination of pregnancy, preterm Birth, and low birth weight, Birth.

Furthermore, in the first trimester of waiting, the maternal thyroid hormones are essential for the unborn child’s correct development of its skeletal and central nervous systems, as long as its own thyroid does not come into operation and produces them autonomously. An untreated condition of maternal hypothyroidism can interfere with the baby’s physical growth and intellectual development. The medical community agrees that marked hypothyroidism should be treated during pregnancy to prevent these damages. In contrast, if hypothyroidism is mild and asymptomatic, the extent of the risk is unclear.

As a precaution, the American Thyroid Association recommends that all women who plan to or do not rule out pregnancy and have symptoms suspected of hypothyroidism, or have no symptoms but have a history of thyroid disease among relatives of the first-degree, have type 1 diabetes or another autoimmune disease, are 30 years of age or older. Based on the tests’ results, it is up to the endocrinologist and gynecologist to decide whether to undertake therapy. Levothyroxine is harmless to the fetus.

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