TPO and hypothyroidism: Summarizing the studies which have been published, the following can be concluded: 1) Overt hyperthyroidism and hypothyroidism have several adverse effects on pregnancy outcomes, 2) The long term effect of overt hypothyroidism on cognitive function has been well documented, 3) There is debate on short and long term effect of subclinical hypothyroidism, 4) Thyroid antibody positivity is associated with adverse pregnancy outcomes, but there is no consensus on feto-maternal complication of pregnant women with TPO antibody positive and euthyroid status.