This landmark NEJM trial showed no benefit in women with TPO antibodies and a TSH > 2.5 of starting levothyroxine. However, most IVF centers start low-dose levothyroxine since subclinical hypothyroidism is associated with an increased risk of miscarriages especially if TSH > 5 or TSH > 2.5 ...

In addition to the TABLET trial in NEJM, there are two additional recent negative trials in the literature: POSTAL and T4LIFE.While there is likely no harm to using low-dose LT4 for TPO Ab-positive euthyroid women pre-conception, there does not appear to be any benefit. However, it is important to f...