Interventions for preventing and treating hyperthyroidism in pregnancy.

BACKGROUND Women with hyperthyroidism in pregnancy have increased risks of miscarriage, stillbirth, preterm birth, and intrauterine growth restriction; and they can develop severe pre-eclampsia or placental abruption. OBJECTIVES To assess the effects of interventions for preventing or treating hyperthyroidism in pregnant women. SEARCH STRATEGY We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (28 July 2010). SELECTION CRITERIA We intended to include randomised controlled trials comparing antithyroid treatments in pregnant women with hyperthyroidism. DATA COLLECTION AND ANALYSIS Two review authors would have assessed trial eligibility and risk of bias, and extracted data. MAIN RESULTS No trials were located. AUTHORS' CONCLUSIONS As we did not identify any eligible trials, we are unable to comment on implications for practice, although early identification of hyperthyroidism before pregnancy may allow a woman to choose radioactive iodine therapy or surgery before planning to have a child. Designing and conducting a trial of antithyroid drugs for pregnant women with hyperthyroidism presents formidable challenges. Not only is hyperthyroidism a relatively rare condition, both of the two main drugs used have potential for harm, one for the mother and the other for the child. More observational research is required about the potential harms of methimazole in early pregnancy and about the potential liver damage from propylthiouracil.