The thyroid gland is located in the front of the neck, below the Adam’s apple, and is shaped like a butterfly. It is responsible for producing thyroid hormones, which control the metabolism of the entire body, as well as the function of many organs, apart from regulating the heart rate. It also affects a woman’s muscles, bones, and menstrual cycle.
A malfunction can cause infertility and also influences during pregnancy, since a decrease in its activity can have serious consequences: natural abortion during the first trimester of pregnancy, premature birth and problems in the brain development of the fetus , even if the mother does not have symptoms of the disease.
We will tell you what is the function of this gland in pregnancy, what are its main alterations and what to do to avoid its possible consequences.
How the thyroid gland interferes with pregnancy
According to the Hospital Clinic de Barcelona, thyroid alterations are the second cause of endocrinological complications during pregnancy , after diabetes.
The clinical protocol carried out by this center, together with the Hospital San Joan de Déu and the Center for Fetal and Neonatal Medicine of Barcelona, explains that during pregnancy the thyroid gland increases the production of hormones by 40-100% to cover maternal needs and fetal.
Therefore, thyroid problems can be difficult to diagnose during pregnancy due to higher levels of thyroid hormones and other symptoms that occur in both pregnancy and thyroid disorders. Detecting and treating a malfunction of this gland is essential to avoid serious complications in pregnancy .
Also, this maternal hormone is important for the baby’s brain development and nervous system . During the first trimester, the fetus depends on the mother’s thyroid hormone supply, which comes through the placenta. Around week 12, the baby’s thyroid begins to work on its own, but does not make enough thyroid hormone until 18-20 weeks into the pregnancy.
Two hormones related to pregnancy, human chorionic gonadotropin (hCG) and estrogen, cause higher levels of thyroid hormone in the blood. During pregnancy, the thyroid is slightly enlarged in healthy women, but not enough for a health care professional to feel during a physical exam.
Thyroid disorders in pregnancy
Hypothyroidism
Hypothyroidism complicates between 0.2% and 1% of pregnancies.
It can be difficult to detect since some of the symptoms are confused with those of pregnancy such as fatigue, constipation, muscle cramps and weight gain.
Other characteristic signs of this thyroid disorder are: cold intolerance, edema, discomfort in the carpal tunnel, dry skin and hair loss.
Regarding the effects that this complication has on pregnancy:
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About 70% of women with untreated hypothyroidism have anovulatory cycles and, consequently, reduced fertility.
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It has been associated with an increase in fetal loss (20%), structural alterations (20%), preeclampsia (44%), anemia (33%), placental abruption (20%), postpartum hemorrhage (20%) and low weight fetal at birth (30%).
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A close link between uncontrolled hypothyroidism and alterations in fetal neurodevelopment has been described: increased risk of impaired neurodevelopment and lower scores in childhood intelligence tests.
All these serious adverse effects seem to disappear or, in any case, decrease if the disease is well controlled and treated , especially from the first trimester.
Hyperthyroidism
Excess thyroid hormone may be due to autoimmune houses (Graves’ disease), or it may be produced temporarily by the pregnancy itself. Its prevalence in pregnancy is low: between 0.1% and 4%.
The same placental hormones can affect the production of the thyroid in pregnant women. In fact, the hormone itself that is used to diagnose pregnancy in the tests used, HCG (chorionic gonadotropin hormone) can stimulate the maternal thyroid gland, especially in the first trimester, and produce transitory hyperthyroidism.
Among its associated symptoms: nervousness, insomnia, tremor, tachycardia, palpitations, increased number of stools, high blood pressure, increased sweating, heat intolerance, weight loss …
In Graves’ disease, a characteristic skin lesion may also be seen.
Effects on pregnancy
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Gestational or transient hyperthyroidism has not been associated with significant effects on the mother or the baby, therefore monitoring it is recommended but not treatment with antithyroid drugs. It is usually associated with severe nausea and vomiting.
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In severe cases, it has been associated with preeclampsia and / or eclampsia, fetal growth restriction (CIR), premature delivery, tachycardia and fetal hyperthyroidism, thyrotoxic crisis (Graves disease) with a maternal mortality of 20-25% and heart failure.
The symptoms of Graves’ disease can be confused with signs or symptoms typical of normal pregnancy, but in the case of hyperthyroid symptoms or suspicious signs such as goiter, it should be studied by means of laboratory tests that include a thyroid profile and an immunological study.
Hashimoto’s thyroiditis
It is the most common cause of hypothyroidism and affects 5% of the adult population.
As explained by the Mayo Clinic, the inflammation of Hashimoto’s disease, also known as chronic lymphocytic thyroiditis, often causes the thyroid gland to become underactive (hypothyroidism).
It mainly affects middle-aged women, but it can also occur in men and women of any age and in children.
Doctors evaluate thyroid function to help detect this disease. Treatment of Hashimoto’s disease with thyroid hormone replacement is generally simple and effective.
Iodine deficiency
This mineral is very important during pregnancy because the thyroid uses it to make thyroid hormone. Also, the baby gets iodine from the mother’s diet. Therefore, the woman will need to consume more iodine during pregnancy (approximately 250 micrograms per day).
Iodine deficiency during pregnancy has been associated with increased miscarriages, fetal and perinatal mortality, low birth weight, and neurodevelopmental disorders. Although iodine supplementation in salt appears to decrease the risk of maternal and fetal hypothyroidism, about one in 20 women have low urine iodine levels.
Dairy products, seafood, eggs, meat, chicken, and iodized salt, which is the one with added iodine, are good sources of iodine.
To avoid deficits, experts recommend, recommend (like other experts) to take a prenatal vitamin with 150 micrograms of iodine to ensure that the pregnant woman is getting enough, especially if she does not use iodized salt.
The best medicine is prevention
The Barcelona protocol explains that most scientific societies recommend universal screening for thyroid dysfunction in the first trimester of pregnancy.
Selective screening would be recommended in pregnant women who present symptoms of thyroid dysfunction or present risk factors for presenting it. And the protocol adds that since there are a large number of pregnant women over 36 years of age, it is advisable to perform a thyroid dysfunction test on all pregnant women in the first trimester of pregnancy.
Regarding the appearance of goiter, it is recommended to carry out thyroid function studies in asymptomatic low-risk pregnant women, since, in normal pregnancy, up to 30% of pregnant women may present alterations in the size of the thyroid gland or nodules. .
According to the Institute of Endocrine Diseases of the United States Department of Health, to detect abnormalities of the thyroid gland in pregnancy, the doctor will review the symptoms and do some blood tests to the woman to measure their levels of thyroid hormone. You can also look for antibodies in the blood to see if Graves disease or Hashimoto’s disease are behind the causes.
If the pregnant woman has mild hyperthyroidism or hypothyroidism, she probably does not need treatment. If your hyperthyroidism is related to hyperemesis gravidarum, you only need treatment for vomiting and dehydration.
If the alteration is more severe, the doctor may prescribe medications with the intention that the thyroid produces less or more thyroid hormones, so that it reaches the baby’s bloodstream in the proper dose.
Via | Thyroid and pregnancy protocol. Hospital Clínic | Hospital Sant Joan de Déu | Barcelona University
Photos | iStock
In Babies and More | Thyroid, fertility and risk of miscarriage in the first months of pregnancy, Thyroid control in pregnant women, The last medical check-ups before childbirth: what they are and when they are carried out
