Last update: Aug. 8, 2017

Maternal Overactive thyroid

Low Risk for breastfeeding

Moderately safe. Probably compatible.
Mild risk possible. Follow up recommended.
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Hyperthyroidism occurs in 1 to 2 of every 1,000 pregnancies (Inoue 2009), with Graves' disease being the most frequent cause (85%: Marx 2008).
It often improves in the third trimester of pregnancy by reducing or suppressing the medication and usually worsens after childbirth, requiring reinstatement or reinforcement of treatment, which is safe for the infant whether it is continued from gestation or if it is instituted during breastfeeding and it does not require monitoring of the thyroid function of the infant, it is enough to monitor adequate physical and psychomotor development (Alexander 2017, Inoue 2009, Marx 2008, Mandel 2001).

There is no data which suggests that hyperthyroidism can affect milk production or breastfeeding in general (Alexander 2017).

Postpartum thyroiditis, with its clinical phases of hyperthyroidism and hypothyroidism, is an autoimmune inflammation that occurs in the first year after birth, with an incidence of 3 to 16% (Serrano 2014, Muller 2001). There is no data to recommend universal screening, but there is in women with type 1 diabetes mellitus or associated depression (Abalovich 2007).

There is controversy over its association with hyperprolactinemia (Sanjari 2016, Onal 2014).

Anti-TSH receptor antibodies (TRAb) can be found in the milk of mothers treated with thyrotoxicosis during the first two months, and may cause transient thyroid disease in the infant (Törnhage 2006), usually hyperthyroidism that may require treatment (Azizi 2011).

During pregnancy and breastfeeding iodine needs are increased, from around 250 micrograms (μg) daily and not exceeding 500 μg daily (Alexander 2017, Serrano 2014, Stagnaro 2011, Abalovich 2007). In areas with severe iodine deficiency and without iodized salt, post-partum administration of a single oral dose of 400 mg of iodized oil ensures an adequate amount of iodine in breast milk for 6 months (Bouhouch 2014).

There is widespread consensus among societies specialized in giving treatment without interrupting breastfeeding (Alexander 2017, Poppe 2012, Lazarus 2012, Mestman 2012). Medication should be administered immediately after breastfeeding (Hudzik 2016).

Propylthiouracil at doses of up to 750 mg daily does not alter thyroid function or normal infant development (Inoue 2009, Glatstein 2009, Marx 2008, Azizi 2006, Bartalena 2005, Momotani 2000 and 1989, Cooper 1987, McDougall 1986, Kampmann 1980). Other authors limit the safe dose to 300-450 mg / day (Alexander 2017, Stagnaro 2011, Mandel 2001).

Methimazole at doses up to 20-30 mg daily does not alter the infant's thyroid function or psychomotor development (Alexander 2017, Serrano 2014, Stagnaro 2011, Inoue 2009, Glatstein 2009, Marx 2008, Azizi 2006, 2003, 2002, 2000 and 1996, Bartalena 2005, Cooper 1987).

Given the risk of hepatic toxicity from propylthiouracil, methimazole is considered to be the preferred treatment for hyperthyroidism, especially during breastfeeding (Hudzik 2016, Serrano 2014, Karras 2012, 2010 and 2009, Azizi 2011).

50 mg of Carbimazol weekly also does not alter the thyroid function nor the normal development of the infant (Bartalena 2005, Verd 1998).

The radioactivity of iodine 131 is concentrated in breast milk and its long half-life necessitates interruption of breastfeeding in both diagnostic and treatment doses (Alexander 2017, Prunty 2016, Serrano 2014, Am.Thyr.Ass 2011, Stagnaro 2011, Abalovich 2007, Azizi 2006, Dydek 1988) and the radioactivity can be measured weekly in milk samples in order to resume it (Saenz 2000).

If required, for diagnostic or control purposes, iodine 123 can be used with a half-life of 13 hours, suspending breastfeeding for about 4 days or Technetium 99m can be used, which requires an interruption of only one day.

Beta-blockers are necessary to control thyrotoxicosis status; propranolol or metoprolol at a sufficient minimum dose are compatible with breastfeeding (Alexander 2017).

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Suggestions made at e-lactancia are done by APILAM´s pediatricians and pharmacists, and are based on updated scientific publications.
It is not intended to replace the relationship you have with your doctor but to compound it.

Jose Maria Paricio, Founder & President of APILAM/e-Lactancia

Your contribution is essential for this service to continue to exist. We need the generosity of people like you who believe in the benefits of breastfeeding.

Thank you for helping to protect and promote breastfeeding.

José María Paricio, founder of e-lactancia.

Other names

Maternal Overactive thyroid is also known as Maternal Hyperthyroidism. Here it is a list of alternative known names::


Maternal Overactive thyroid belongs to this group or family:


  1. Alexander EK, Pearce EN, Brent GA, Brown RS, Chen H, Dosiou C, Grobman WA, Laurberg P, Lazarus JH, Mandel SJ, Peeters RP, Sullivan S. 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. Thyroid. 2017 Abstract Full text (link to original source) Full text (in our servers)
  2. Prunty JJ, Heise CD, Chaffin DG. Graves' Disease Pharmacotherapy in Women of Reproductive Age. Pharmacotherapy. 2016 Abstract
  4. Hudzik B, Zubelewicz-Szkodzinska B. Antithyroid drugs during breastfeeding. Clin Endocrinol (Oxf). 2016 Abstract
  5. Serrano Aguayo P, García de Quirós Muñoz JM, Bretón Lesmes I, Cózar León MV. Tratamiento de enfermedades endocrinológicas durante la lactancia. [Endocrinologic diseases management during breastfeeding.] Med Clin (Barc). 2015 Jan 20;144(2):73-9. Abstract
  6. Bouhouch RR, Bouhouch S, Cherkaoui M, Aboussad A, Stinca S, Haldimann M, Andersson M, Zimmermann MB. Direct iodine supplementation of infants versus supplementation of their breastfeeding mothers: a double-blind, randomised, placebo-controlled trial. Lancet Diabetes Endocrinol. 2014 Abstract
  7. Onal ED, Saglam F, Sacikara M, Ersoy R, Cakir B. Thyroid autoimmunity in patients with hyperprolactinemia: an observational study. Arq Bras Endocrinol Metabol. 2014 Abstract
  8. Karras S, Krassas GE. Breastfeeding and antithyroid drugs: a view from within. Eur Thyroid J. 2012 Abstract Full text (link to original source) Full text (in our servers)
  9. Lazarus JH. Pre-conception counselling in graves' disease. Eur Thyroid J. 2012 Abstract Full text (link to original source) Full text (in our servers)
  10. Poppe K, Hubalewska-Dydejczyk A, Laurberg P, Negro R, Vermiglio F, Vaidya B. Management of Hyperthyroidism in Pregnancy: Results of a Survey among Members of the European Thyroid Association. Eur Thyroid J. 2012 Abstract Full text (link to original source) Full text (in our servers)
  11. Mestman JH. Hyperthyroidism in pregnancy. Curr Opin Endocrinol Diabetes Obes. 2012 Abstract
  12. Speller E, Brodribb W. Breastfeeding and thyroid disease: a literature review. Breastfeed Rev. 2012 Abstract
  13. Azizi F, Amouzegar A. Management of hyperthyroidism during pregnancy and lactation. Eur J Endocrinol. 2011 Abstract Full text (link to original source) Full text (in our servers)
  14. Fumarola A, Di Fiore A, Dainelli M, Grani G, Carbotta G, Calvanese A. Therapy of hyperthyroidism in pregnancy and breastfeeding. Obstet Gynecol Surv. 2011 Abstract
  15. American Thyroid Association Taskforce On Radioiodine Safety., Sisson JC, Freitas J, McDougall IR, Dauer LT, Hurley JR, Brierley JD, Edinboro CH, Rosenthal D, Thomas MJ, Wexler JA, Asamoah E, Avram AM, Milas M, Greenlee C. Radiation safety in the treatment of patients with thyroid diseases by radioiodine 131I : practice recommendations of the American Thyroid Association. Thyroid. 2011 Abstract Full text (link to original source) Full text (in our servers)
  16. Stagnaro-Green A, Abalovich M, Alexander E, Azizi F, Mestman J, Negro R, Nixon A, Pearce EN, Soldin OP, Sullivan S, Wiersinga W; American Thyroid Association Taskforce on Thyroid Disease During Pregnancy and Postpartum.. Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and postpartum. Thyroid. 2011 Abstract Full text (link to original source) Full text (in our servers)
  17. Karras S, Tzotzas T, Kaltsas T, Krassas GE. Pharmacological treatment of hyperthyroidism during lactation: review of the literature and novel data. Pediatr Endocrinol Rev. 2010 Abstract
  18. Inoue M, Arata N, Koren G, Ito S. Hyperthyroidism during pregnancy. Can Fam Physician. 2009 Abstract Full text (link to original source) Full text (in our servers)
  19. Glatstein MM, Garcia-Bournissen F, Giglio N, Finkelstein Y, Koren G. Pharmacologic treatment of hyperthyroidism during lactation. Can Fam Physician. 2009 Abstract Full text (link to original source) Full text (in our servers)
  20. Karras S, Tzotzas T, Krassas GE. Antithyroid drugs used in the treatment of hyperthyroidism during breast feeding. An update and new perspectives. Hormones (Athens). 2009 Abstract Full text (link to original source) Full text (in our servers)
  21. Marx H, Amin P, Lazarus JH. Hyperthyroidism and pregnancy. BMJ. 2008 Abstract Full text (link to original source) Full text (in our servers)
  22. Abalovich M, Amino N, Barbour LA, Cobin RH, De Groot LJ, Glinoer D, Mandel SJ, Stagnaro-Green A. Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2007 Abstract Full text (link to original source) Full text (in our servers)
  23. Koren G, Soldin O. Therapeutic drug monitoring of antithyroid drugs in pregnancy: the knowledge gaps. Ther Drug Monit. 2006 Abstract Full text (link to original source) Full text (in our servers)
  24. Azizi F. Treatment of post-partum thyrotoxicosis. J Endocrinol Invest. 2006 Abstract
  25. Törnhage CJ, Grankvist K. Acquired neonatal thyroid disease due to TSH receptor antibodies in breast milk. J Pediatr Endocrinol Metab. 2006 Abstract
  26. Bartalena L, Tanda ML, Bogazzi F, Piantanida E, Lai A, Martino E. An update on the pharmacological management of hyperthyroidism due to Graves' disease. Expert Opin Pharmacother. 2005 Abstract Full text (link to original source) Full text (in our servers)
  27. Azizi F. Thyroid function in breast-fed infants is not affected by methimazole-induced maternal hypothyroidism: results of a retrospective study. J Endocrinol Invest. 2003 Abstract
  28. Azizi F, Bahrainian M, Khamseh ME, Khoshniat M. Intellectual development and thyroid function in children who were breast-fed by thyrotoxic mothers taking methimazole. J Pediatr Endocrinol Metab. 2003 Abstract
  29. Azizi F, Hedayati M. Thyroid function in breast-fed infants whose mothers take high doses of methimazole. J Endocrinol Invest. 2002 Abstract
  30. Mandel SJ, Cooper DS. The use of antithyroid drugs in pregnancy and lactation. J Clin Endocrinol Metab. 2001 Abstract Full text (link to original source) Full text (in our servers)
  31. Muller AF, Drexhage HA, Berghout A. Postpartum thyroiditis and autoimmune thyroiditis in women of childbearing age: recent insights and consequences for antenatal and postnatal care. Endocr Rev. 2001 Abstract Full text (link to original source) Full text (in our servers)
  32. Azizi F, Khoshniat M, Bahrainian M, Hedayati M. Thyroid function and intellectual development of infants nursed by mothers taking methimazole. J Clin Endocrinol Metab. 2000 Abstract Full text (link to original source) Full text (in our servers)
  33. Momotani N, Yamashita R, Makino F, Noh JY, Ishikawa N, Ito K. Thyroid function in wholly breast-feeding infants whose mothers take high doses of propylthiouracil. Clin Endocrinol (Oxf). 2000 Abstract
  34. Saenz RB. Iodine-131 elimination from breast milk: a case report. J Hum Lact. 2000 Abstract
  35. Verd S, Cardo E. Well-being of a baby breast fed by her mother on carbimazol treatment. J Hum Lact. 1998 Abstract
  36. Azizi F. Effect of methimazole treatment of maternal thyrotoxicosis on thyroid function in breast-feeding infants. J Pediatr. 1996 Abstract
  37. Momotani N, Yamashita R, Yoshimoto M, Noh J, Ishikawa N, Ito K. Recovery from foetal hypothyroidism: evidence for the safety of breast-feeding while taking propylthiouracil. Clin Endocrinol (Oxf). 1989 Abstract
  38. Dydek GJ, Blue PW. Human breast milk excretion of iodine-131 following diagnostic and therapeutic administration to a lactating patient with Graves' disease. J Nucl Med. 1988 Abstract Full text (link to original source) Full text (in our servers)
  39. Cooper DS. Antithyroid drugs: to breast-feed or not to breast-feed. Am J Obstet Gynecol. 1987 Abstract
  40. McDougall IR, Bayer MF. Should a woman taking propylthiouracil breast-feed? Clin Nucl Med. 1986 Abstract
  41. Kampmann JP, Johansen K, Hansen JM, Helweg J. Propylthiouracil in human milk. Revision of a dogma. Lancet. 1980 Abstract

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