Adequate maternal thyroid function is important for fertility, conception and an uncomplicated pregnancy [Toloza, 2022], with thyroid hormone imbalances during conception and pregnancy having well-documented negative effects on both mother and baby. The contents and implications for clinical practice of new guidelines from the American Thyroid Association will form the basis of this podcast. Most women with pre-existing treated hypothyroidism require an increase in levothyroxine dose of 30–50% as soon as pregnancy is confirmed to remain euthyroid during gestation [Li, 2020] but their TSH levels should be closely monitored to avoid over- or under-treatment [Pearce, 2022]. Current evidence suggests women with serum TSH levels >10 mIU/L in the first trimester should be treated with levothyroxine right away [Pearce, 2022; Razvi, 2023], and women who are not treated need to be followed-up to ensure that treatment is initiated promptly, if indicated. Despite the potential impact on the development of the baby, the diagnosis and treatment of subclinical hypothyroidism is still controversial in pregnancy [Gietka-Czernel, 2021] with current recommendations not supporting universal screening of low-risk women during pregnancy [Sullivan, 2019]. However, increased awareness is needed for women who are at risk of hypothyroidism post-partum, particularly if their serum TSH levels were >4.0 mU/L at <8 weeks gestation and their TPOAb levels were ≥300 μIU/mL [Gao, 2021]. This includes both women with subclinical hypothyroidism before they were pregnant, and those who developed hypothyroidism in the first trimester. Testing thyroid function should be considered at 6–12 weeks post-partum for high-risk populations, followed by periodic testing due to high lifetime risk of developing permanent hypothyroidism [Peng, 2022].