Information and support For professionals Positive antibodies with normal thyroid function In women with positive thyroid peroxidase antibodies (TPOab) with TSH and FT4 within the reference range, there is an increased risk of later developing hypothyroidism. It is also associated with an increased risk of miscarriage, preterm birth and thyroid function abnormalities postpartum. Is treatment needed? Levothyroxine treatment, however, is not recommended as it does not reduce these risks if the thyroid function is normal. (TABLET trial NEJM 2019) Before pregnancy Monitor thyroid function monitored every 6 months while planning a pregnancy. During pregnancy Recheck thyroid function at 7-9 weeks and again at 20 weeks. Repeat TPOab testing is not needed. If women are found to be hypothyroid, treat with levothyroxine. Read the RCOG Green-top guideline on the Management of Thyroid Disorders in Pregnancy Manage Cookie Preferences Please ensure Javascript is enabled for purposes of website accessibility