Effects of Levothyroxine on The Risk of Miscarriage in Pregnant Euthyroid Women with Thyroid Autoantibody-Positive: A Meta-Analysis

Objective To investigate the effect of levothyroxine （LT4） treatment on abortion in euthyroid women with positive thyroid autoantibodies（TAI）. Methods Three groups of keywords related to “thyroid autoimmune”, “abortion” and “thyroid hormone” were searched online or by hand. Data were searched among PubMed, EMBASE, Cochrane Library, Wanfang medical database,CNKI from January 2000 to April 2019. Collection of prospective and retrospective literatures on LT4 treatment of euthyroid pregnant women with positive thyroid autoantibodies. Quality of the extracted literature were evaluated by Newcastle- Ottawa-Scale （NOS）. Meta- analysis was performed by RevMan 5.3 software. Results （1） The study included 7 articles, 6 were cohort studies, and 1 was a case-control study. All of them were English literatures. NOS score results: 6 were rated 7~9 points （for high-quality literature）. 1 was rated 6 points （for medium-quality literature）. （2） The meta-analysis showed that the odds ratio value of miscarriage risk for TAI pregnant women treated with LT4 was 0.80, 95% confidence interval was 0.59~1.09, P=0.15. Conclusion LT4 does not reduce the risk of a miscarriage in pregnant women with TAI with intact thyroid function.