[Hypothyroidism: from the desire for pregnancy to delivery]

The link between hypothyroidism and infertility is still a matter of debate. Hypothyroidism can result in cycle disturbances, such as oligomennorhea and functional bleeding. Additionally, several studies have shown that thyroid autoimmunity (detection of anti peroxydase antibodies) may account for the occurrence of repetitive miscarriages. In infertility work-up, screening thyroid function should be specifically recommended for women with clinical hypothyroidism, with a personal, familial history of thyroid or other auto immune diseases (such as type I diabetes) as well as for women with unexplained anovulation or functional bleeding. Moreover, detection of thyroid antibody seems to be worthwhile for the assessment of recurrent miscarriages, due to the potential benefit of thyroid supplementation. In pregnant women, assessment of thyroid function seems specifically crucial to ensure adequate foetal development. Indeed, it has been well established that untreated maternal hypothyroidism may be associated with disturbances of brain development and low intellectual quotient. Additionally, other foetal (growth deficiency, premature birth, low birth weight) as well as maternal (gestational hypertension, pre-eclampsia...) complications have been also reported in pregnant women with untreated hypothyroidism. Consequently, screening of thyroid function should be performed in every woman at risk of thyroid disease. Recent studies even advocate that thyroid screening should be extended to the overall pregnant population. The objective is to adjust L-thyroxin supplementation to maintain serum TSH concentrations below the threshold of 2.5 mUI/l. Finally, iodine deficiency, currently observed in pregnant women, should be prevented by iodine supply prior to conception, during pregnancy and during breast feeding as well.