Thyroid disease commonly presents in women in their reproductive years. Maternal, fetal and neonatal outcomes are very good if the diagnosis is made early and appropriate management pathways are established. In the uncommon situation of concurrent maternal and fetal disease, the key management issues involve recognition of the involvement of the fetus and close intensive surveillance of both mother and fetus/neonate using a multi-disciplinary approach. This approach, utilising a combination of serial ultrasound of the fetus and serial biochemical testing for the mother, allows for the accurate titration of medical therapy to both patients.