Effect of thyroxine treatment on pregnancy outcomes in infertile Japanese women with TSH levels between 2.5 μIU/mL and the upper reference limit: a retrospective study

Abstract

Recent randomized controlled studies have revealed that levothyroxine (LT4) treatment improves pregnancy outcomes only in infertile women with subclinical hypothyroidism who have thyroid autoantibodies (TAs), but not for those with high TSH levels within the normal range who have TAs. Here, we retrospectively investigated pregnancy outcomes in infertile Japanese women with 2.5 μIU/mL ≤ TSH < upper reference limit (URL). Between 2012 and 2018, 286 patients diagnosed with infertility were followed for more than 1 year at our institution. Among them, we included 106 patients with 2.5 μIU/mL ≤ TSH < URL. We divided these patients into four groups based on the combination of TA positivity and LT4 treatment status to assess the effects of LT4 treatment considering TA positivity on the incidence of pregnancy or miscarriage. In this study, we did not find any significant differences in the rates of pregnancy or miscarriage among the four groups (p = 0.81 and 0.52, respectively). In addition, logistic regression analysis showed that age and history of miscarriage were associated with the incidence of pregnancy, but presence of TAs and LT4 treatment status were not and that no variables examined were associated with the incidence of miscarriage. In summary, we were not able to demonstrate the benefit of LT4 treatment for pregnancy outcomes in Japanese euthyroid infertile women with 2.5 μIU/mL ≤ TSH < URL regardless of TA status in this study.

The impact of levothyroxine therapy on pregnancy and neonatal outcomes in euthyroid pregnant women with thyroid autoimmunity: A systematic review, meta-analysis and trial sequential analysis

“…Overall, 3 RCTs were at a high risk of bias (Negro et al, 2006;Negro et al, 2016;Nazarpour et al, 2017), 2 RCTs had some concerns (moderate risk of bias) (Negro et al, 2005;Wang et al, 2017), and 1 RCT were at a low risk of bias (Dhillon-Smith et al, 2019). For cohort studies, 4 studies were at a high risk of bias (Revelli et al, 2009;Lepoutre et al, 2012;Mosaddegh et al, 2012;Dal Lago et al, 2021), and 1 study was at moderate risk of bias (Tsunemi et al, 2021).…”

“…studies(Negro et al, 2005;Negro et al, 2006; Revelli et al, 2009;Lepoutre et al, 2012;Mosaddegh et al, 2012;Negro et al, 2016;Nazarpour et al, 2017;Wang et al, 2017;Dhillon-Smith et al, 2019;Dal Lago et al, 2021;Tsunemi et al, 2021) comprising 2,901 euthyroid pregnant women with thyroid autoimmunity were included. These studies took place in a variety of countries: 3 RCTs and 2 cohort studies in Italy, 1 RCT and 1 cohort study in Iran, 1 RCT in China, 1 RCT in United Kingdom, 1 cohort study in Japan and 1 cohort study in Belgium.…”