Why are pregnant women prone to thyroid disease?

The article was written by Specialist Doctor II Le Thi My - Director of the Center for Thyroid Pathology - Department of Diagnostic Imaging and Nuclear Medicine - Vinmec Times City International Hospital

Thyroid disorders are diverse, affecting 1% to 2% of pregnant women. When a pregnant woman has thyroid disease, it will have many serious effects on the mother and the fetus. Therefore, timely detection and treatment of thyroid disease during pregnancy will reduce dangerous complications. Treatment of thyroid disease in pregnant women is still complicated, requiring the participation of an endocrinologist and an obstetrician.

The thyroid gland is the largest endocrine gland in the body, with a butterfly shape located in the front and bottom of the neck. Thyroid hormone plays an important role in regulating metabolism, regulating the body's energy release process. Thyroid hormone also affects brain development, breathing, heart and nervous system functions, body temperature production, muscle strength, skin, menstrual cycle,....
Pathology Thyroid gland is very diverse, especially during pregnancy, it changes the physiological activity of the thyroid gland and can change the course of thyroid disease, affecting 1% to 2% of pregnant women. pregnant. Thyroid problems related to pregnancy include:
Hypothyroidism: A condition in which the thyroid gland does not produce enough thyroid hormone. Hypothyroidism can originate in the thyroid, pituitary, or hypothalamus. Hyperthyroidism : An overproduction of thyroid hormone, this syndrome is less common than hypothyroidism Goiter (simple goiter): This is not a specific disease. A goiter can be related to hypothyroidism, hyperthyroidism, or even abnormal thyroid function. Thyroid nodules: These are abnormal tumors or masses located inside the thyroid gland. Thyroid nodules can be caused by thyroid cysts, benign thyroid nodules, or thyroid cancer. Thyroid cancer: More common in adult women than in men or young adults. There are different types of thyroid cancer, depending on the specific type of cells inside the thyroid gland. Most cases of thyroid cancer have a good prognosis and high survival rates, especially those patients who are diagnosed at an early stage.

During pregnancy, the mother's physiological activity and thyroid function have many changes, which can lead to thyroid diseases or dysfunction during pregnancy, specifically:
Hormonal Changes During pregnancy, the mother's body produces two main hormones: βhCG (human chorionic gonadotropin) and estrogen. An increase in βhCG during the first trimester of pregnancy can cause a slight decrease in the hormone TSH (thyroid stimulating hormone), which is called subclinical hyperthyroidism. TSH will rise again later in pregnancy. Estrogen (female sex hormone) will increase serum protein-binding thyroid hormone, however free thyroid hormone (FT3, FT4) does not increase, thus does not affect thyroid function. Increases peripheral metabolism of thyroid hormone. Immune changes
Autoimmune phenomena appear or increase in the first trimester of pregnancy, improving in the second trimester to the end of pregnancy. Antibodies to TPO and thyroglobulin are present in 6 to 20% of pregnant women. The presence of these antibodies may be associated with: Increased likelihood of miscarriage, subclinical hypothyroidism in pregnancy, depression, and postpartum thyroiditis.
Levels of anti-thyroid antibodies decrease in the first trimester of pregnancy, peak in the third trimester, and then rise again in the postpartum period. These antibodies can cross the placenta causing thyroid dysfunction in the fetus and neonate.
Change in size
The thyroid gland can change in size during pregnancy: About 10-15% larger in size, called a goiter. This rate is higher among women living in mountainous areas where iodine deficiency is present.
Changes in iodine requirements during pregnancy
During pregnancy, the need for iodine increases by 50% due to an increase in the body's metabolism, increased renal clearance of iodine, and iodine for the needs of the fetus. Therefore, the maternal thyroid gland increases its activity to capture iodine and synthesize thyroid hormones. Thyroid volume can be increased by 10% where iodine is sufficient, and 20-40% in areas of iodine deficiency. It can be said that during this period, if the iodine supply is not enough, thyroid dysfunction may appear.

During the first 13 weeks of pregnancy, the fetus does not have a thyroid gland, so it must completely depend on the amount of thyroid hormone provided by the mother through the placenta. This stage is the period of formation and division of fetal organs, so if there is a lack of hormones during this time, complications are very serious.
Thyroid dysfunction in pregnant women is mainly hypothyroidism. Consequences of hypothyroidism in the mother are hypertension, premature delivery, placental abruption, even miscarriage, stillbirth. For the fetus, when born, the child has mental retardation.
Hyperthyroidism in pregnant women is less common, about 1.7% of pregnant women have this disease. Consequences of hyperthyroidism cause complications such as low birth weight, miscarriage, preeclampsia, premature birth... Even acute hyperthyroidism during labor causes death for both mother and child with a high rate of death. up to 100%.
Screening for the timely detection and treatment of thyroid diseases in pregnant women is very important. In addition to preventing complications and reducing mortality in both mother and child, it ensures that babies are born with perfect physical and intellectual health... The lower the chance of complications in both mother and baby will be.

Pregnant women at high risk of thyroid disease who need to be screened for thyroid disease during pregnancy include:
Pregnant women with pre-diagnosed thyroid disease and/or undergoing medical treatment. thyroid gland such as Basedow , hypothyroidism , simple goiter , thyroid nodule ; History of radiation therapy to the head, face and neck; Having a family history of close relatives (father, mother, sister...) with thyroid disease; Pregnant women who have had thyroid disease in previous pregnancies; Having a history of bad obstetrics such as miscarriage, stillbirth, premature delivery, birth of a child with birth defects; Patients with type 1 diabetes; Having autoimmune diseases such as rheumatoid arthritis, lupus... Thyroid disease, especially thyroid dysfunction in pregnant women, if not detected and intervened in time, the disease can leave behind dangerous complications. Therefore, pregnant women, especially those at high risk, should undergo clinical screening and blood tests for the hormones FT4 and TSH. For suspected cases, the doctor may order more thyroid ultrasound and some special blood tests. Pregnant women with a well-diagnosed thyroid dysfunction will receive timely intervention and treatment.
Vinmec International General Hospital has established a CENTER for Thyroid Pathology, where you will receive:
Examination - consultation by a team of experienced doctors and experts, trained in developed countries World leader in the management and intensive treatment of thyroid disease. You will be examined, examined, evaluated and tested with a system of modern machines and equipment that meet international standards (the GE Logiq S8 ultrasound machine integrates tissue-elastic ultrasound technology – a The latest ultrasound technology in thyroid disease diagnosis, 3 Tesla magnetic resonance imaging machine....) The personalized multi-specialty treatment model will make it the best condition for you to be examined and cared for. Treatment with the most optimal regimen - most suitable for you and complete peace of mind during the pregnancy.