Abstract
Adequate control of thyroid function is crucial for optimal pregnancy outcomes and neurodevelopment of the offspring, and testing for thyroid function is ideally performed using manufacturer- and gestation-specific reference ranges. While universal screening for thyroid dysfunction is not recommended, targeted case finding of women at risk of thyroid disease during pregnancy is advised. A number of controversies continue to fuel debate including: (i) the target range for thyroid stimulating hormone (TSH) in women with subfertility planning pregnancy, (ii) management of mild thyroid hypofunction before and during pregnancy, (iii) the treatment of thyroid peroxidase (TPO) antibody-positive euthyroid women with levothyroxine, (iv) the optimal choice of antithyroid treatment in women with hyperthyroidism. A significant body of evidence has accumulated in recent years, including large systematic reviews and meta-analyses of observational studies determining effects of thyroid dysfunction on pregnancy and fetal outcomes. In addition, outcomes from important randomised trials continue to inform current guidance on how to best care for women with thyroid dysfunction before and during pregnancy.