Can Hypothyroidism Cause Miscarriage?

Doctor checking a patient's glands

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If you've been diagnosed with hypothyroidism — or an underactive thyroid — you may be wondering if it may cause problems during pregnancy or even a miscarriage. In fact, hypothyroidism is linked to miscarriages so it's important to be able to recognize the signs of this condition. 


The thyroid is a gland in your neck (above your collarbone) that produces hormones involved with many of your body's activities. It plays an important role in your body's metabolic and hormone balance. When something's off with your thyroid, there's a good chance the rest of your body and its processes — including pregnancy — will be affected.

What Is Hypothyroidism?

Thyroid hormone controls your body's metabolic processes. When you have hypothyroidism, the thyroid does not produce enough thyroid hormone to keep these processes going at their normal rate, and they start slowing down. This can affect many aspects of your health, including whether you have a healthy pregnancy.

Hypothyroidism in Pregnancy

It's important that your thyroid is functioning normally during your pregnancy, both for your health and your developing baby's health. There are several complications that can occur in pregnant women with hypothyroidism:

Miscarriage Risk

Research suggests that having an underactive thyroid may be linked with some types of pregnancy loss. Studies have found that subclinical hypothyroidism (SCH) could mean an increased risk of placental abruption and preterm delivery, both of which can result in later pregnancy loss.

The evidence is less clear about a link between hypothyroidism and first-trimester miscarriage. Some studies suggest that thyroid autoimmunity (TAI) may be linked to first-trimester miscarriage, but other studies contradict the link and the matter is still up for debate.

A Chinese study published in 2014 found that women with both subclinical hypothyroidism and thyroid autoimmunity have a greater risk of miscarriage between weeks 4 and 8 of their pregnancies. 


According to the U.S. National Library of Medicine, symptoms of hypothyroidism include:

  • A puffy face
  • Cold intolerance
  • Constipation
  • Decreased sweating
  • Depression
  • Dry skin
  • Dry, thinning hair
  • Fatigue
  • Heavy or irregular menstrual periods and fertility problems
  • Joint and muscle pain
  • Slowed heart rate
  • Weight gain

If you are concerned that you may have hypothyroidism, ask your doctor about screening. They can make a diagnosis based on your symptoms and a simple blood test.


If you do have an underactive thyroid, you will be treated with a synthetic thyroid hormone called levothyroxine. Synthetic levothyroxine is identical to your natural thyroid hormone and is safe for your developing baby.

If you were already on levothyroxine before you got pregnant, your doctor will probably increase your dose during your pregnancy to maintain your normal thyroid function. It's best to talk to your doctor about your dose before you become pregnant. During your pregnancy, your thyroid function should be checked every 4 weeks until mid pregnancy and then at least once close to 30 weeks.

6 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. US National Library of Medicine. Thyroid diseases.

  2. Maraka S, Ospina NM, O'keeffe DT, et al. Subclinical Hypothyroidism in Pregnancy: A Systematic Review and Meta-Analysis. Thyroid. 2016;26(4):580-90.  doi:10.1089/thy.2015.0418

  3. Lazzarin N, Moretti C, De felice G, Vaquero E, Manfellotto D. Further evidence on the role of thyroid autoimmunity in women with recurrent miscarriage. Int J Endocrinol. 2012;2012:717185.  doi:10.1155/2012/717185

  4. Liu H, Shan Z, Li C, et al. Maternal subclinical hypothyroidism, thyroid autoimmunity, and the risk of miscarriage: a prospective cohort study. Thyroid. 2014;24(11):1642-9.  doi:10.1089/thy.2014.0029

  5. US National Library of Medicine. Hypothyroidism.

  6. Alexander EK, Pearce EN, et al., 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease during Pregnancy and the Postpartum. Thyroid. 2017;(10)5:3-7. doi:10.1089/thy.2016.0457

Additional Reading
  • Allan, W.C., J.E. Haddow, G.E. Palomaki, J.R. Williams, M.L. Mitchell, R.J. Hermos, J.D. Faix, R.Z. Klein, "Maternal thyroid deficiency and pregnancy complications: implications for population screening." J Med Screen 2000.

  • Casey, Brian M., Jodi S. Dashe, C. Edward Wells, Donald D. McIntire, William Byrd, Kenneth J. Leveno, and F. Gary Cunningham, "Subclinical Hypothyroidism and Pregnancy Outcomes." Obstetrics & Gynecology 2005.

  • Hypothyroidism. MedlinePlus. U.S. National Library of Medicine.

  • Pregnancy and Thyroid Disease. National Institute of Diabetes and Digestive and Kidney Diseases.

  • Sieiro, Netto L., C. Medina Coeli, E. Micmacher, S. Mamede Da Costa, L. Nazar, D. Galvao, A. Buescu, and M. Vaisman, "Influence of thyroid autoimmunity and maternal age on the risk of miscarriage." Am J Reprod Immunol Nov 2004.

  • Subclinical Hypothyroidism Increases Early Miscarriage Risk. Medscape.

  • Thyroid Disease and Pregnancy. American Thyroid Association.

By Krissi Danielsson
Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage.