Levothyroxine treatment and pregnancy outcomes in women with subclinical hypothyroidism: a systematic review and meta-analysis
To evaluate the benefits of LT4 treatment on pregnancy outcomes in SCH women.
PubMed [including Medline], Web of Science, Wiley, Google Scholar, Science direct and Scopus were searched for identifying and retrieving all English articles published up to May 2018 on the effects of levothyroxine treatment on pregnancy outcomes in pregnant women with SCH compared to untreated or healthy controls. In this systematic review and meta-analysis, both fixed and random effect models were applied to estimate the pooled effect size. Heterogeneity and publication bias were evaluated using the I-squared (I2) and Begg’s statistics, respectively. We also explored heterogeneity sources using meta-regression models and sensitivity analysis.
Data of 13 cohort studies and randomized controlled trials with a total of 11,503 participants were analyzed. This meta-analysis showed that pregnant women with SCH treated with levothyroxine had lower chances of pregnancy loss (OR 0.78, 95% CI 0.66–0.94; I2 = 0%) and higher chances for live birth rates (OR 2.72, 95% CI 1.44–5.11; I2 = 25%) than the placebo group. Compared to euthyroid women, SCH patients treated with levothyroxine had higher odds ratio for preterm labor (OR 1.82, 95% CI 1.14–2.91; I2 = 0%).
Results of this study showed that the effects of treatment with levothyroxine in SCH pregnant women are not the same for all pregnancy outcomes. Levothyroxine treatment in these patients can reduce pregnancy loss. Considering the limited number of studies available, further studies are warranted to document more precise data on other consequences.
KeywordsSubclinical hypothyroidism Pregnancy Outcome Treatment
The authors wish to acknowledge Ms. Niloofar Shiva for critical editing of English grammar and syntax of the manuscript.
SN was involved in study design, search in databases, studies selection, data analysis, manuscript drafting, and submitting manuscript. FRT was involved in study design, data analysis, manuscript drafting and critical discussions. MA contributed in data analysis, and critical discussion, execution and manuscript drafting. RBY contributed in statistical analysis, interpreting data and manuscript drafting. FA was involved in data analysis, manuscript drafting, revising and critical discussion.
This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
This systematic review and meta-analysis study was approved by the ethics committee of the Research Institute of Endocrine Sciences (RIES) (approval no.: IR.SBMU.ENDOCRINE.REC.1397.126).
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