INTRODUCTION: Hyperthyroidism is characterised by high levels of serum thyroxine and triiodothyronine, and low levels of thyroid-stimulating hormone. The main causes of hyperthyroidism in pregnancy are Graves' disease and chorionic gonadotrophin (hCG)-mediated hyperthyroidism.

METHODS AND OUTCOMES: We conducted a systematic review and aimed to answer the following clinical question: What are the effects of antithyroid drug treatments for hyperthyroidism in pregnancy? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2014 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS: We found no studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS: In this systematic review we present information relating to the effectiveness and safety of the following interventions: antithyroid drugs (carbimazole/thiamazole and propylthiouracil).