Effect of levothyroxine on pregnancy outcomes in women with thyroid autoimmunity: a systematic review with meta-analysis of randomized controlled trials.

ABSTRACT

OBJECTIVE: To investigate whether levothyroxine is associated with improved live birth and other benefits in women with thyroid autoimmunity. DESIGN: Systematic review and meta-analysis. SETTING: Not applicable. PATIENT(S) Women positive for thyroid peroxidase antibody. INTERVENTION(S) MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials were searched without any language restrictions. Pooled effect sizes were calculated using random-effects models. MAIN OUTCOME MEASURE(S) The primary outcome was the incidence of live birth, miscarriage, preterm birth, clinical pregnancy, ectopic pregnancy, neonatal admission, and birth weight. The summary measures were reported as relative risk (RR) with 95% confidence interval. RESULT(S) Levothyroxine supplementation was not associated with an increased rate of live birth or a decreased risk of miscarriage. Results were similar in subgroup analyses of live birth by age, baseline thyrotropin, baseline thyroid peroxidase antibody, body mass index, and use of assisted conception. For live birth, the effect estimate lay within the futility boundary for RR of 20% and 15%, but at a 10% RR, the effect estimate lay between the futility boundary and the inferior boundary. CONCLUSION(S) High- to moderate-quality evidence demonstrated that the use of levothyroxine was not associated with improvements in clinical pregnancy outcomes among women positive for thyroid peroxidase antibody. REGISTRATION NUMBER PROSPERO CRD42019132976.