The thyroid is a gland in the lower neck. It makes hormones that regulate growth, brain development, and metabolism. Hypothyroidism is a low or absent production of these hormones. Congenital means the condition is present since birth.

The Thyroid Gland

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If this condition is not treated it can cause damage to the brain. This can lead to intellectual disability and abnormal growth.


In most cases, the cause is unknown, but it is probably genetic. The most common known causes are abnormal development of the thyroid gland or a defect in producing thyroid hormone. About 15% of cases are inherited.

Babies may have a temporary shortage in their thyroid hormones. This is more common in babies born before 40 weeks.

Risk Factors

Factors that may increase the chance of congenital hypothyroidism include:

  • Medication during pregnancy, such as radioactive iodine therapy
  • Maternal autoimmune disease
  • Too much iodine during pregnancy
  • Family history of congenital hypothyroidism


Symptoms or signs take time to develop. The symptoms of congenital hypothyroidism may include the following:

  • Puffy face
  • Coarse facial features
  • Dull look
  • Thick protruding tongue
  • Poor feeding
  • Choking episodes
  • Constipation or reduced stooling
  • Yellow skin color— jaundice
  • Short stature
  • Swollen abdomen
  • Decreased activity
  • Sleeps a lot
  • Rarely cries or hoarse cry
  • Dry brittle hair; low hairline
  • Poor muscle tone
  • Cool and pale skin
  • Poor weight gain due to poor appetite
  • Poor growth
  • Difficult breathing
  • Low temperature
  • Swollen hands, feet and genitals


At birth, most infants are screened for this condition. Blood tests will be able to identify thyroid levels. Images of the thyroid may also be taken with:

  • Thyroid scan (technetium)
  • Nuclear imaging (scintigraphy)


The outcome is best if the condition is caught early. It is important to start treatment before the brain and nervous system are fully developed. If treatment is given early, it can prevent damage. Left untreated, the condition will lead to poor mental development and delayed growth.

Medication will treat the hypothyroidism. The medication will replace the missing hormone.

Once medication starts, the levels of thyroid hormones are checked often. This will help to keep the values within a normal range. If values are kept within a normal range, there are no side effects or complications.


Most cases cannot be prevented. The following are some things the mother can do during pregnancy to reduce the risk:

  • Avoid radioactive iodine treatment or iodine as antiseptic during pregnancy
  • Consume enough, but not too much iodine during pregnancy

American Thyroid Association

Genetics Home Reference


Health Canada

Thyroid Foundation of Canada


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Bongers-Schokking JJ, Koot HM, et al. Influence of timing and dose of thyroid hormone replacement on the development in infants with congenital hypothyroidism. J Ped. 2000;136(3):292-297.

Castanet M, Polak M, Leger J. Familial forms of thyroid dysgenesis. Endocr Dev. 2007;10:15-28.

Gruters A, Krude H, Biebermann H. Molecular genetic defects in congenital hypothyroidism. Europ J Endocr. 2004;151 Suppl 3:U39-U44.

Congenital hypothyroidism. EBSCO DynaMed Plus website. Available at: Updated March 24, 2016. Accessed November 28, 2017.

LeFranchi SH, Austin J. How should we be treating children with congenital hypothyroidism. J Pediatr Endocrinol Metab. 2007;20(5):559-578.

Last reviewed November 2018 by EBSCO Medical Review Board James Cornell, MD  Last Updated: 12/20/2014