Whether a woman is pregnant or not, there is no difference in treating hypothyroidism. Untreated hypothyroidism may have effects on pregnancy in different ways.
Pregnancy and Hormones
Pregnancy comes with various hormonal and physiological changes. An increase in estrogen and progesterone levels are associated with pregnancy as they are the major pregnancy hormones. The level of hormones changes drastically. A woman produces more estrogen in a single pregnancy then a woman will create throughout her life without being pregnant. Apart from these, levels and functions of various other hormones changes during pregnancy as well.
Thyroid Hormones and Pregnancy
Introduction to Thyroid Gland
The thyroid gland is a two inches long gland located in the front side of the neck just below the cricoid cartilage (Adam’s apple) and is found wrapped around the trachea. It is a butterfly-shaped gland weighing 0.52 ounces (15 grams). The two lobes of the gland are similar to butterfly wings attached with a middle part known as the isthmus.
The function of the Thyroid gland
The thyroid gland plays an essential role in the production and storage of the body’s thyroid hormones. During hormones production, the gland requires a signal from specific areas of the brain that are pituitary gland and hypothalamus. After receiving the signal, the brain releases a thyroid-stimulating hormone (TSH), which eventually results in the production of thyroid hormones by the gland. An adequate amount of iodine, either from food as a mineral or from iodized salt, is necessary for maintaining a constant level of these hormones.
Thyroid Hormones and Pregnancy
The major hormones produced by the thyroid gland are triiodothyronine (T3) and thyroxine (T4). These hormones are involved in metabolism (a process that transforms food into energy), maintaining blood pressure, body temperature, muscle strength, cholesterol level, and even the heart rate. Another hormone produced by the thyroid gland is calcitonin, which plays a vital role in calcium metabolism. All these hormones are regulated by the release of thyroid-stimulating hormone (TSH) produced by the pituitary gland in the brain.
During pregnancy, the level of thyroid hormone varies as it is concerned with the growth and development of the baby’s brain and nervous system. In the first three months (first trimester) of pregnancy, the baby depends on the mother for thyroid hormones, and it is exchanged through the mother’s placenta. After almost 12 weeks, the fetus develops its thyroid gland. That’s the time when it starts producing the thyroid hormones but still depends on mother until around 18 weeks.
It is necessary to ensure the presence of an adequate amount of iodine in pregnant females because thyroid hormone production depends on it. Thus, an appropriate level of iodine could be achieved through the intake of prenatal vitamins with enough iodine. This will ensure that the baby gets the required amount of iodine from the mother.
Pregnancy and Thyroid Disease
The imbalance in thyroid hormones can result in complications for the human body. Sometimes any abnormality associated with the thyroid gland could cause an increase or decrease from the normal level of these hormones. Too much production occurs when the gland becomes overactive, and this condition is known as hyperthyroidism. This condition results in speeding up metabolism. Contrary to this, when the thyroid gland becomes underactive, and the body functioning slows down, the state is called hypothyroidism.
Human chorionic gonadotropin (HCG) and estrogen are two hormones related to pregnancy that can increase thyroid levels. Thus, making it difficult to diagnose thyroid disease in pregnant women. Yet your healthcare professional will be able to diagnose the complication through the symptoms. Even though it is necessary to get yourself regularly checked for the thyroid problems, it is equally important to get it checked if you are pregnant or are planning to get pregnant.
Moreover, it is important to know that through regular thyroid function tests and proper medication, one can protect the baby’s health and can have a healthy pregnancy.
Hypothyroidism and Pregnancy
Women of childbearing age are prone to thyroid disease. Thus, it is common to have thyroid disease-associated complications during pregnancy. These complications can equally affect the mother and baby.
Etiology of Hypothyroidism
One of the major etiologic factors of hypothyroidism is Hashimoto’s thyroiditis. It is an autoimmune disorder in which the body’s immune system produces antibodies and attacks the thyroid gland. This could result in the enlargement of the thyroid gland, called a goiter. Lack of an adequate amount of iodine in your diet can also cause hypothyroidism and goiter both. Treatment of hyperthyroidism that includes radioactive iodine therapy or thyroid surgery, may also result in hypothyroidism. But in most cases, the specific cause of hypothyroidism remains unknown.
Clinical Features of Hypothyroidism
Hypothyroidism occurs when the production of thyroid hormones is reduced by the thyroid gland. As a result, slowing down the metabolism and causing various symptoms. In the beginning, the clinical features of hypothyroidism are not noticeable and remain asymptomatic. Symptoms develop with time and can end up in more severe ones. Slowing down of the metabolism means the body will lack energy, and some of the common hypothyroidism associated symptoms are weight gain, fatigue, muscular cramps, weakness, joint pain, slow heart rate, and shortness of breath with activity, etc. Symptoms can also include a hoarse voice, constipation, brittle hair, itchy skin, hair loss, brittle nails, loss of sex drive, etc. In severe conditions, it might lead to clinical features including difficulty in concentration and learning in the baby born to hypothyroid mother, irregular menstrual cycle, infertility, and might results in miscarriage as well.
Effects of Hypothyroidism on the Pregnant Mother
Females who have undiagnosed hypothyroidism before they get pregnant may contribute to severe complications later. Pregnancy and hypothyroidism come with some common features. Thus it is essential to get yourself checked for hypothyroidism. As even a mild but untreated hypothyroidism can develop complications for the mother and fetus both. Hypothyroidism associated with pregnancy complications includes miscarriage, anemia, premature birth, abruptio placentae, preeclampsia (a sudden rise in blood pressure in the third trimester of pregnancy), and postpartum hemorrhage. In rare cases, it might result in congestive heart failure.
The reason for irregular periods associated with hypothyroidism is that it prevents ovulation, i.e., the release of the egg from the ovary. Usually, after a monthly cycle, an egg is released from the ovary, but in those who develop hypothyroidism, the frequency of egg release reduces as a result affecting the normal menstrual cycle. Moreover, the increased risk of miscarriage is because hypothyroidism interferes with embryo development.
Effects of Hypothyroidism on the Fetus
Thyroid hormones are vital for the development of the baby’s nervous system. If a mother suffering from hypothyroidism remains undiagnosed on untreated, especially during the first trimester, it can adversely affect the baby’s brain. This is because, during the first three months, the fetus solely depends on the mother for its thyroid hormones. Thus, hypothyroidism could interfere with normal development and can cause low IQ problems as well as impaired psychomotor (mental and motor) development in the baby. Also, if you have untreated hypothyroidism during pregnancy, there are chances for you to have a premature baby with weighing less than normal and have lowered brain development.
Researched says that babies born to mothers with thyroid diseases are at increased risk of brain, heart, and kidney defects. As thyroid hormones are crucial for babies ’ development and can affect their intellectual development, they also increase the risk of physical abnormalities like an extra finger, ear deformities, or cleft palate.
Hypothyroidism and Breastfeeding
Thyroid hormones are involved in normal breast development. Hypothyroidism causes a lack of the production of thyroid hormones as a result of affecting breast development and, eventually, milk production. Treated mothers show no issues in the milk supply, but those with untreated conditions struggle with the adequate supply of milk. Furthermore, it is safe for a breastfeeding mother to continue with thyroid medication.
It is common to know that hypothyroidism might affect pregnancy and the production of milk. But some females may develop thyroid disease after giving birth to the child. Indeed, breastfeeding helps the baby to nourish and grow, yet it can affect the level of thyroid hormones in the mother. A breastfeeding mother can develop an increased production of thyroid hormones, which can lead to a condition called postpartum thyroiditis. It is good to know that over a certain period, this condition goes away on its own, and in case of prolonged duration, doctors can prescribe a low dose of medicine.
In contrary to this, there is enough evidence available that supports the prevention of thyroid problems associated with breastfeeding. It says that breastfeeding can help prevent thyroid problems in both the mother and the baby. One can prevent autoimmune thyroid disease as well as thyroid cancer through regular breastfeeding.
Diagnosis of Hypothyroidism
For the diagnosis of hypothyroidism, the main test that is recommended by the doctors is measuring blood levels of TSH. The higher level of TSH in blood depicts that the pituitary gland has responded and made more TSH, but it is remained unused to produce sufficient thyroid hormone. Other blood tests include measuring the T4 levels, which is a hormone directly produced by the thyroid gland. A low level of T4 in blood would indicate hypothyroidism.
Some of the reasons that tend to make a woman at higher risk of developing thyroid diseases are a family history of thyroid disease, type 1 diabetes mellitus, thyroid autoimmunity, or it can be any other autoimmune condition. Thus, for diagnosis, it is important to tell the doctor every detail about your history. It would be an ideal condition if every woman when gets pregnant or is planning to get pregnant, should be tested for the presence of thyroid disease. Otherwise, prenatal counseling can be carried out after conceiving. It is recommended that the females who are a higher risk for developing thyroid disease should get the TSH level checked or carry out thyroxine blood tests or any other thyroid blood tests to have a healthy pregnancy.
Frequent Monitoring of the Thyroid Levels
The incorrect doses can adversely affect health as well, so regular monitoring is important. For example, in case of a higher dose of thyroid replacement hormone, women may end up in developing treatment-induced hyperthyroidism. That means the metabolism of your body suddenly increased the required level. As a result, treatment-induced hyperthyroidism can cause osteoporosis (bone loss and bone thinning), nervousness, and heart palpitations.
Even if the dose of your hypothyroidism is adjusted, it is necessary to have blood levels checked regularly. Because hypothyroidism is a progressive disease with can stay there for your whole life. So, regardless of whether you are pregnant or not, it is better not to leave it ignored. The dose adjustment can vary over the period.
Dr Martin receives his MD from University of Iowa. His expertise includes microbiology, anatomy and clinical psychology. He also dedicates himself to continuous learning in different fields.
