Information and support I am Living with a thyroid condition Managing subclinical hypothyroidism in conception and pregnancy What is subclinical (borderline) hypothyroidism? Subclinical hypothyroidism (SCH) is defined as either having: A TSH greater than the upper limit of the non-pregnancy range and below 10 mU/L with normal FT4 before pregnancy. A TSH greater than the upper limit of the pregnancy reference range and below 10 mU/L during pregnancy. Your doctor will have the pregnancy reference ranges and will be able to make the diagnosis for you. Do I need treatment? If you are planning a pregnancy, or are pregnant, and have subclinical hypothyroidism it is usually recommended that you are treated with levothyroxine if you develop it before the 2nd and 3rd trimesters. This is to reduce your risk of developing overt hypothyroidism and having associated complications during pregnancy. Before pregnancy Your care will be managed by your GP. Start treatment with levothyroxine. If you are started on levothyroxine treatment for SCH, the guidance is the same as for women with overt hypothyroidism. During pregnancy If SCH is detected in the 1st trimester start treatment with levothyroxine. If SCH is detected in the 2nd and 3rd trimesters, you may only need monitoring with regular thyroid function tests, as it is not always needed to start. Levothyroxine treatment after the 1st trimester. After birth Stop taking levothyroxine if you were not taking it before your pregnancy. Get your thyroid function checked, usually during your 6-week postnatal check. 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