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Logo of bmjThis ArticleThe BMJ
BMJ. 2007 August 25; 335(7616): 362.
PMCID: PMC1952486
Hypothyroidism in Pregnancy

Three unresolved issues

Joanna Girling, consultant obstetrician and gynaecologist1 and Catherine Nelson-Piercy, consultant obstetric physician2

We disagree with three points in the article on unresolved questions in managing hypothyroidism in pregnancy.1

Firstly, the data regarding pregnancy outcome for women with treated hypothyroidism are conflicting, weakened by poor standardisation of important obstetric variables, and at most may indicate an association, but certainly not a causal relation, with thyroid function.2

Secondly, there are no data to support the view that driving down the upper limit of thyroid stimulating hormone (TSH) to 2.5 mU/l is safe3 or that it helps maternal or fetal wellbeing.2

Thirdly, as there is some evidence4 that excess thyroxine may be harmful, the authors' bold statement that the dosage should normally be incremented by 30-50% is not an evidence based answer to the unresolved question of the article's title, and routine increases in thyroxine should not be recommended until or unless it becomes clear that this will benefit either the mother or the baby.


Competing interests: None declared.


1. Glinoer D, Abalovich M. Unresolved questions in managing hypothyroidism during pregnancy. BMJ 2007;335:300-2. (11 August.) [PMC free article] [PubMed]
2. Hypothyroidism in pregnant women. Drugs Therapeutics Bull 2006;44:53-6.
3. Brabant G, Beck-Peccoz P, Jarzab B, Laurberg P, Orgiazzi J, Szabolcs I, et al. Is there a need to redefine the upper normal limit for TSH? Eur J Endocrinol 2006;154:633-7. [PubMed]
4. Anselmo J, Cao D, Karrison T, Weiss RE, Refetoff S. Fetal loss associated with excess thyroid hormone exposure. JAMA 2004;292:691-5. [PubMed]

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