The thyroid gland makes an important hormone (thyroid) for carrying out a fundamental function in human body- metabolism. When there is excessive production of thyroid by the gland, it leads to a condition called hyperthyroidism (overactive thyroid). Hyperthyroidism essentially may not be a damaging condition or life threatening in itself.
However, when it couples with pregnancy, it may create damaging consequences both for the mother and her unborn child. Pregnancy itself is a crucial stage of life and hyperthyroidism needs treatment as it may complicate health conditions.
Effects Of Hyperthyroidism In Pregnancy
Hyperthyroidism can bring many adverse effects on pregnancy and even affect after child birth. When hyperthyroidism is due to Grave’s disease, pregnant women can have a pattern of worsening and improving their conditions. With advancement in pregnancy, pregnant women can require reduced doses of anti-thyroid medications to treat the condition.
Hyperthyroidism can cause pregnancy-induced hypertension, placental abruption, thyroid storm and even heart failure. Low birth weight, hyperthyroidism, hypothyroidism and goiter may be some of the fetal consequences. When hyperthyroidism is uncontrolled, it can increase the risk of severe pre-eclampsia in pregnant women.
The adverse effects of hyperthyroidism can be more alarming and noticeable in women who are diagnosed for the first time in pregnancy. Although rare, neonatal hypothyroidism may be found in infants whose mothers have Graves’ hyperthyroidism; this can be the outcome of the (transplacental) transport of mother’s anti-thyroid drugs. Among all forms of uncontrolled hyperthyroidism, the Graves’ disease form can complicate pregnancies most.
Unfortunately, the diagnosis of hyperthyroidism in pregnancy is not easy because blood tests may show skewed results owing to the pregnancy itself. High levels of thyroid hormones (T3 and T4) and low level of thyroid stimulating hormone (TSH) mark hyperthyroidism.
Since thyroid disorders are prevalent in women of child-bearing age, it is important to correct the condition for maternal and fetal well being. Since there is a natural increase in demand for the thyroid hormones during pregnancy, it may lead to worsening of an overlooked/unattended thyroid disorder. There is suggestive recommendation regarding screening of all pregnant women for thyroid disorder.
Treatment Of Hyperthyroidism
Hyperthyroidism can be treated and controlled through various ways. The post-treatment outcomes are generally encouraging both for the mother and her unborn child.
Treatment should aim at controlling the condition with restricted medications owing to their safety concerns in pregnancy. Uncontrolled administration of drugs can be harmful for the fetus. Anti-thyroid drugs can be used to treat hyperthyroidism in pregnant women depending upon their suitability.
For example, Propylthiouracil is a popular drug for treating hyperthyroidism during pregnancy in North America. In many other nations, like Europe and Asia, methimazole can be the preferred drug for treating hyperthyroidism. There is a conflicting opinion about methimazole’s usage for treating hyperthyroidism in pregnancy.
There is a suggestion that methimazole may lead to congenital abnormalities like facial abnormalities, aplasia cutis, etc. This indicates the popularity and preference for Propylthiouracil over methimazole in many nations.
Another reason to suspect methimazole is restricted transplacental transfer of propylthiouracil as against methimazole. Nonetheless, methimazole gained wide acceptance as an alternative to propylthiouracil in North America for those who cannot tolerate propylthiouracil.
Carbimazole, which can also be used to treat hyperthyroidism, needs careful administration because it crosses the placenta. When consumed in high doses, it may lead to fetal hypothyroidism and goitre. Occasionally, there may be a scalp defect in the fetus.
Regular preconception counseling is crucial for those wanting or planning for pregnancy in near future. It helps gain an insight into the safety of drugs for treating the condition during pregnancy. Absence of any treatment or discontinuation of treatment can be dangerous to the mother and her unborn child; it may even lead to death.
A pregnant woman can get adequate care during her pregnancy through skilful association between her family members and her doctor. Usually, hyperthyroidism in pregnancy can remain well controlled. A woman should prefer to have spontaneous vaginal delivery restricting caesarean section only to obstetric indications.
Therapy And Surgery For Hyperthyroidism In Pregnancy
Thyroid hormones being crucial for (fetal) brain development, over treating hyperthyroidism can also be detrimental. Mild hyperthyroidism can be attended through therapy as far as condition remains suggestive. Radioactive iodine therapy reaches the fetal thyroid gland and is not suggested during pregnancy.
Surgery of the thyroid gland in pregnancy may be done, but is not common. Allergies or non-adherence to drugs, side effects of medications, suspected malignancy, etc. may indicate surgical treatment of hyperthyroidism in pregnancy. Surgical procedure can be carried out safely during the second or early third trimester of pregnancy.