Thyroid Disorders in Pregnancy

Overview

Definition

The thyroid is a butterfly-shaped gland in the front of the neck. Pregnancy hormones can cause changes to thyroid hormone levels. This can raise the risk of pregnancy problems when it is not treated. There are two types of problems:

  • Hypothyroidism —the thyroid gland does not make enough thyroid hormone
  • Hyperthyroidism —the thyroid gland makes too much thyroid hormone
The Thyroid Gland
IMAGE
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Causes

Hypothyroidism in pregnancy may be caused by:

  • An immune system problem known as Hashimoto disease, the most common cause
  • Not enough treatment for pre-existing hypothyroidism
  • Over treating hyperthyroidism

Hyperthyroidism in pregnancy may be caused by:

  • Overactivity of the thyroid gland known as Graves disease, the most common cause
  • Very high levels of human chorionic gonadotropin (hCG)

Risk Factors

Things that may raise the risk of this problem are:

  • A personal or family history of a thyroid problem
  • Having been treated for a thyroid problem
  • An enlarged thyroid gland (goiter)
  • Hyperemesis gravidarum , a severe form of morning sickness
  • A personal or family history of problems with the immune system

SymptomsandDiagnosis

Symptoms

Hypothyroidism problems are:

  • Tiredness
  • Dry skin
  • Constipation
  • Weight gain
  • Slow heartbeat
  • Memory problems
  • Depression

Hyperthyroidism problems are:

  • Losing weight without trying
  • Sweating
  • Shaking
  • Nervousness
  • Diarrhea
  • Problems sleeping
  • Bulging eyes
  • Fast or abnormal heart rhythm

Diagnosis

The doctor will ask about your symptoms and health history. A physical exam will be done.

Your thyroid hormone levels will be tested. Other blood tests may also be done.

Images may be taken of the thyroid.

Treatments

Treatment

Hypothyroidism

Medicine will be given to replace the hormone. Thyroid levels will be checked often and the dose may need to be changed.

Hyperthyroidism

Mild hyperthyroidism will be watched closely. Some people may need to take medicine. Your medicine needs may change during pregnancy. Your doctor will check your thyroid hormone levels every 6 to 8 weeks during pregnancy and 4 weeks after a change in dose.

If medicine does not work, the thyroid gland may need to be removed. Radioiodine is used to destroy the thyroid gland. It is rarely done during pregnancy because of the risk to the fetus.

Prevention

There are no known methods to prevent this health problem. Proper prenatal care can help to find problems before they happen.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.

RESOURCES

The American Congress of Obstetricians and Gynecologists http://www.acog.org 

American Thyroid Association http://www.thyroid.org 

CANADIAN RESOURCES

The Society of Obstetricians and Gynaecologists of Canada https://sogc.org 

Thyroid Foundation of Canada http://www.thyroid.ca 

References

American College of Obstetricians and Gynecologists. Practice Bulletin No. 148: Thyroid disease in pregnancy. Obstet Gynecol. 2015;125(4):996-1005.

Graves disease in adults. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/graves-disease-in-adults. Accessed August 24, 2021.

Hashimoto’s disease. Family Doctor—American Academy of Family Physicians website. Available at: https://familydoctor.org/condition/hashimotos-disease. Accessed August 24, 2021.

Pregnancy & thyroid disease. National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: https://www.niddk.nih.gov/health-information/endocrine-diseases/pregnancy-thyroid-disease. Accessed August 24, 2021.

Smith TJ, Hegedüs L. Graves' Disease. N Engl J Med. 2016 Oct 20;375(16):1552-1565, commentaries can be found in N Engl J Med 2017 Jan 12;376(2):184, N Engl J Med 2017 Jan 12;376(2):185.