Thyroid disease is a medical condition that is related to the thyroid gland, which is present in the neck region. The gland secretes thyroid hormones, which when produced in inadequate quantities can cause hypothyroidism, and when produced in excess, leads to hyperthyroidism.
These hormones are responsible for carrying out metabolic activities in the body, and at the same time, also influences the development of children, among other things. It has been projected that the burden of thyroid disease in the Indian population is about 42 million, with women more susceptible to it.
While planning a pregnancy, women must ensure that they are in good health to avoid complications during the pregnancy period, and to ensure that the child is healthy. This includes keeping the thyroid hormone levels in check, as they have an important role to play in the gestation period. The mother’s thyroid hormones travel through the placenta and to the growing foetus, until the second trimester begins, when it is able to produce its own; this is required for the development of the foetal brain and nervous system.
After a woman has conceived, the level of two hormones–oestrogen and human chorionic gonadotropin (hCG)–increases, that in turn, also increase the levels of thyroid hormone.
Diagnosing a thyroid disorder, especially hyperthyroidism, during pregnancy may be difficult since similar manifestations can be attributed to both. The symptoms can also vary depending on the condition one has.
Symptoms for hypothyroidism during pregnancy include muscle cramps, increased sensitivity to cold temperature, difficulty in concentrating, as well as pregnancy-like characteristics of fatigue and weight gain. In case of hyperthyroidism, common symptoms include extreme tiredness, increased sensitivity to heat, irregular and increased heart rate, difficulty falling asleep, weight loss, and severe nausea and vomiting.
In addition to inadequate treatment of abnormal thyroid levels, thyroid disease during pregnancy may be a result of certain autoimmune disorders.
Hashimoto thyroiditis is an autoimmune disease, wherein the immune system produces antibodies to destroy the cells of the thyroid gland; this leads to lesser than required secretion of thyroid hormones over time. In addition to symptoms common to hypothyroidism, it can also manifest in the form of dry skin, constipation, joint stiffness, muscle weakness, sensitivity to cold, and swelling in extremities.
Another autoimmune disease, Graves’ disease is characterised by the production of antibodies called thyroid stimulating immunoglobulin (TSI), causing the secretion of more than normal levels of thyroid hormone. This can lead to heat intolerance, high blood pressure, palpitations, irregular menstruation, diarrhoea, and insomnia. The indicators for Graves’ disease are high during the beginning, and at the end of the pregnancy. They only improve in the second and third trimesters, due to a decrease in TSI production.
Since these hormones play a vital role in the child’s growth, and travels to its bloodstream through the placenta, an imbalance can cause complications. Unchecked and untreated thyroid levels can affect both the mother and the baby. The child may be born prematurely, and might have a low birthweight; in some cases, a stillbirth or miscarriage may also occur. Due to the thyroid hormones’ role in the development of the brain, hypothyroidism can lead to low IQ in the child.
In case the mother was treated for Graves’ disease before or during the pregnancy, the body will continue to make the TSI antibody, which can make its way to the baby. Increased levels of TSI in the baby’s bloodstream will result in high thyroid levels in them as well. Weight gain, fast heart rate, irritability, and difficulty in breathing are a few consequences of this condition that can endanger the child’s life.
The mother may be diagnosed with anaemia, and may also experience extreme high blood pressure causing preeclampsia. Hyperemesis gravidarum (vomiting and dehydration) may be a result of hyperthyroidism during pregnancy.
After giving birth, postpartum thyroiditis (thyroid inflammation), which can be characterised by hypothyroidism and/or hyperthyroidism may occur in the mother. Postpartum thyroiditis has a mean prevalence of 7.5% in the female population, and it has been found that women with type-1 diabetes are three times more susceptible to this condition.
It is imperative that the mother’s medical history is talked about thoroughly with doctors during consultation, and they must be kept in the loop in case of any side-effects.
Doctors prescribe medication that is a functionally adequate substitute for thyroid hormone to make up for hypothyroidism – this is usually for thyroxine or T4. When hyperthyroidism is mild, medication is usually not given, unless it is a case of hyperemesis gravidarum, where medicines to control vomiting and dehydration are prescribed. Low doses of antithyroid hormone are given to women with severe hyperthyroidism.