MedicalResearch.com Interview with:
Professor Tianpei Hong, MD, PhD
Of behalf of Prof. Jie Qiao and all the coauthors,
Director, Department of Endocrinology & Metabolism
Director, Department of Laboratory Medicine
Peking University Third Hospital
MedicalResearch.com: What is the background for this study?
- Women who test positive for thyroid autoantibodies have been reported to be at 2- to 3-fold higher risk of spontaneous miscarriage than those who test negative. However, the effect of levothyroxine on miscarriage among women with positive thyroid autoantibodies and normal thyroid function has been documented in limited studies with conflicting results.
- Given the substantial difficulty achieving successful pregnancy among infertile women, identifying optimal treatment for infertile women who test positive for thyroid autoantibodies is particularly important. There are a few randomized clinical trials showing a beneficial effect of levothyroxine treatment on pregnancy outcomes among women undergoing in vitro fertilization and embryo transfer (IVF-ET). However, the sample size of those trials was rather small which may weaken the quality of the evidence.
- Therefore, the Pregnancy Outcomes Study in euthyroid women with Thyroid Autoimmunity after Levothyroxine (POSTAL) study was conducted in Peking University Third Hospital to evaluate whether levothyroxine treatment initiated before IVF-ET could decrease the miscarriage rate and improve the live birth rate in infertile women who tested positive for antithyroperoxidase antibody but had normal thyroid function.
MedicalResearch.com: What are the main findings?
- In this open-label randomized clinical trial involving 600 women who tested positive for antithyroperoxidase antibody and were being treated for infertility, the miscarriage rate was 10.3% among women who received and 10.6% among those who did not receive levothyroxine, and the live birth rates were 31.7% among women who received and 32.3% among those who did not receive the treatment.
Levothyroxine treatment for infertile women with positive thyroid autoantibodies and normal thyroid function did not appear to improve pregnancy outcomes.
MedicalResearch.com: What should readers take away from your report?
- In the POSTAL study, levothyroxine treatment could not decrease the miscarriage rate or increase the live birth rate among women undergoing IVF-ET who tested positive for thyroid autoantibodies but had normal thyroid function. Even in women with a thyroid-stimulating hormone (TSH) level of 2.5 mIU/L or higher before IVF-ET, stratified analysis by the TSH level did not change our findings. Levothyroxine treatment did not appear to improve pregnancy outcomes in this population of women undergoing IVF-ET.
- We recommend against levothyroxine treatment for women undergoing IVF-ET who test positive for thyroid autoantibodies but have normal thyroid function. Levothyroxine treatment should be started after pregnancy when TSH level exceeds the upper limit of the local normal range of pregnancy.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
- Since previously published cohort studies showed conflicting results regarding the effects of thyroid autoantibodies on pregnancy outcomes of IVF-ET, it is necessary to clarify whether thyroid autoantibodies adversely affect pregnancy outcomes of IVF-ET in large-scale cohort studies.
- There are two other ongoing randomized clinical trials, the T4-life study and the TABLET study, in this area. We hope they will provide us with additional high-quality evidence.
MedicalResearch.com: Is there anything else you would like to add?
- New evidence from the Effects of Aspirin in Gestation and Reproduction (EAGeR) study suggested that among fecund women with a history of pregnancy loss, a TSH level of more than 2.5 mIU/L or presence of thyroid autoantibodies were not associated with fecundity, pregnancy loss, or live birth. In addition, the Dutch cohort study published in 2016 showed that high maternal concentrations of free thyroxine are negatively associated with child brain development, which made the problem more complicated. So, more studies are needed before we can clearly address this issue. At the moment, we should avoid overtreatment for pregnant women with positive thyroid autoantibodies and normal thyroid function.
MedicalResearch.com: Thank you for your contribution to the MedicalResearch.com community.
Haining Wang, Hongwei Gao, Hongbin Chi, Lin Zeng, Wenhua Xiao, Yanrong Wang, Rong Li, Ping Liu, Chen Wang, Qing Tian, Zehong Zhou, Jin Yang, Ye Liu, Rui Wei, Ben Willem J. Mol, Tianpei Hong, Jie Qiao. Effect of Levothyroxine on Miscarriage Among Women With Normal Thyroid Function and Thyroid Autoimmunity Undergoing In Vitro Fertilization and Embryo TransferA Randomized Clinical Trial. JAMA. 2017;318(22):2190–2198. doi:10.1001/jama.2017.18249
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