Hypothyroidism and pregnancy
Hypothyroidism in pregnancy carries a risk of many complications that affect both the mother and the baby. Hypothyroidism is a condition in which the production of the thyroid gland hormones triiodothyronine (T3) and thyroxine (T4) is partially or completely suppressed. The most common causes of hypothyroidism are Hashimoto's disease (chronic lymphocytic thyroiditis), the condition after thyroid surgery, and the condition after treatment with radioactive iodine. Diagnosing hypothyroidism before pregnancy can help prevent many complications during pregnancy and childbirth.
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1. Epidemiology of hypothyroidism in pregnancy
Apparent, symptomatic hypothyroidism is diagnosed in approximately 0.5% of pregnant women. In 2-3% of pregnant women, the subclinical form of hypothyroidism is diagnosed, which precedes its full-blown form. Subclinical hypothyroidism is characterized by elevated levels of thyrotropin (TSH) with normal levels of thyroid hormones. Even the subclinical form of hypothyroidism is associated with an increased incidence of complications in pregnancy, e.g. it leads to an increased risk of miscarriage. The risk of developing Hashimoto's disease is high among women who suffer from autoimmune disorders such as vitiligo or pernicious anemia, or who have a family history.
The level of thyroid hormones should be tested before a planned pregnancy. A woman diagnosed with hypothyroidism can be treated endocrinologically and prepare for pregnancy by increasing the dose of levothyroxine accordingly. Some diagnoses of hypothyroidism are not made until pregnancy. The risk of developing complications depends on when the disease was diagnosed and when treatment was started.
2. Risk factors of hypothyroidism
Currently, there are no routine recommendations for TSH testing in women planning or pregnant. The attending gynecologist should pay special attention to pregnant women who:
- have enlarged thyroid lobes, the so-called I prefer,
- previously treated for thyroid dysfunction,
- come from families with a burdened history (thyroid diseases occur in the family),
- come from families with autoimmune diseases,
- suffer from autoimmune diseases,
- were diagnosed due to infertility,
- have previously had a premature birth or a miscarriage.
3. Symptoms of hypothyroidism in pregnancy
During pregnancy, the course of hypothyroidism can be unusual and difficult to diagnose. In some pregnant women, hypothyroidism is asymptomatic or the symptoms are minor. The most frequently reported complaints due to hypothyroidism in pregnancy include: excessive weight gain in relation to the gestational age, feeling cold, dry skin, constipation, drowsiness and a feeling of weakness. Some of the symptoms of the disease during pregnancy are difficult to interpret, such as weight gain or fatigue. Other symptoms of hypothyroidism are: memory impairment, hoarseness, yellowing of the body, hyperkeratosis of the epidermis, swelling of the face and hands, brittle nails, slow heart rate, muscle weakness, calf cramps, anemia. If hypothyroidism is diagnosed, treatment with an endocrinologist is necessary.
4. The influence of hypothyroidism on mother and child
Hypothyroidism may be one of the causes of infertility in women. Hypothyroidism during pregnancy increases the risk of miscarriage, detachment of the placenta, anemia, gestational hypertension and postpartum bleeding. The most dangerous thing for fetal development is maternal hypothyroidism in the first twelve weeks of pregnancy. During this time, the fetal thyroid gland does not yet produce its own hormones, so it needs them from the mother. In women with hypothyroidism, levothyroxine tablets are given, which "replaces" physiologically produced hormones with a healthy thyroid gland.
The presence of thyroid hormones is essential in the first trimester of pregnancy, because during this period organogenesis takes place, i.e. the formation of organs important for the life of the fetus, including the central nervous system. Untreated or improperly treated hypothyroidism in pregnancy may result in the following complications for the fetus and newborn: low birth weight, respiratory disorders, increased risk of fetal death or neonatal death. In addition, children of mothers with hypothyroidism during pregnancy often have neuropsychological disorders, decreased IQ, and learning difficulties.
5. Diagnosis and treatment of hypothyroidism in pregnancy
The basic test in the diagnosis of thyroid function is the measurement of TSH concentration. Before pregnancy, the determination of TSH levels is supplemented with the testing of free thyroid hormones. During pregnancy, the result of TSH concentration can be influenced by many factors, therefore the assessment of thyroid function is difficult. Therefore, in a pregnant woman with suspected hypothyroidism, it is advisable to test free thyroid gland hormones with reference to the standards applicable for a given trimester of pregnancy. If diagnosed with hypothyroidism in pregnancy, anti-thyroid antibody testing should be performed.
A woman diagnosed with hypothyroidism planning a pregnancy should see an endocrinologist. Treatment of a thyroid disorder consists in administering appropriate doses of levothyroxine. A slight excess of levothyroxine in the first months of pregnancy is not as important for the fetus as its deficiency. If hypothyroidism was diagnosed before pregnancy, the doctor starts treatment by gradually increasing the dose of the drug. When hypothyroidism is diagnosed only during pregnancy, the aim is to correct the hypothyroidism as quickly as possible by giving the target dose of the drug straight away. The dose of the drug depends on the woman's body weight and is appropriately adjusted under the control of TSH and T4 levels. The concentration of TSH should not exceed 2.5 IU / ml. Hormone levels are tested before you take your morning dose of levothyroxine.