Effect of moderately increased thyroid‐stimulating hormone levels and presence of thyroid antibodies on pregnancy among infertile women

Abstract

PurposeTo study the effects of mildly elevated thyroid‐stimulating hormone (TSH) levels and thyroid antibodies on pregnancy rates among infertile women and their potential contribution to prolonged infertility treatment.MethodsThis case‐control study included 1479 women who underwent infertility treatment between March 2015 and August 2017. Cumulative pregnancy and miscarriage rates after assisted reproductive technology (ART) or non‐ART treatments were compared between women with TSH <2.5 mIU/L and those with TSH 2.5‐3.5 mIU/L and between women with and without thyroid antibody positivity.ResultsThe cumulative pregnancy rate of women with TSH 2.5‐3.5 mIU/L was similar to that of women with TSH <2.5 mIU/L in the non‐ART (hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.56‐1.23) and ART (HR, 1.17; 95% CI, 0.93‐1.47) groups. Thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) had no correlation with cumulative pregnancy rates. In the non‐ART and ART groups, HRs for TgAb were 0.87 (95% CI, 0.55‐1.32) and 1.09 (95% CI, 0.84‐1.39) and HRs for TPOAb were 0.88 (95% CI, 0.52‐1.39) and 1.29 (95% CI, 0.97‐1.68), respectively.ConclusionsCumulative pregnancy rates and miscarriage rates were similar between women with TSH <2.5 mIU/L and those with TSH 2.5‐3.5 mIU/L and were independent of thyroid antibody positivity.

High-Normal Preconception TSH Levels Have No Adverse Effects on Reproductive Outcomes in Infertile Women Undergoing the First Single Fresh D5 Blastocyst Transfer

“…Chai et al also reported that the clinical pregnancy rate and miscarriage rate were not impaired when the TSH level was high-normal [ 8 ]. In agreement with our results, So et al and Unuane et al both claimed that cumulative pregnancy rates were similar between women with low TSH levels and those with high-normal TSH levels [ 4 , 7 ].…”

“…However, there is insufficient evidence indicating an association between mildly elevated preconception TSH (2.5-4.0 mIU/L) and the abovementioned reproductive outcomes [3]. In recent years, studies investigating the impact of mildly elevated TSH levels on infertile women have emerged [4][5][6][7][8][9][10][11][12][13][14]. However, when infertile women underwent in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI) treatment, the conclusion of the impact of mildly elevated TSH levels on miscarriage and obstetric outcomes in women of reproductive age was still inconsistent in different studies, in which various confounders (such as the transfer of cleavage embryo or blastocysts, the number and quality of the transferred embryo, and the age of included women) influenced the reproductive outcomes.…”

The Impact of Preconception TSH on the Reproductive Outcomes of Infertile Women Undergoing the First Fresh D3 Embryo Transfer Cycle

“…Chai et al also reported that the clinical pregnancy rate and miscarriage rate were not impaired when the TSH level was high-normal [ 8 ]. In agreement with our results, Unuane et al and So et al both claimed that cumulative pregnancy rates were similar between women with low-TSH levels and those with high-normal TSH levels [ 5 , 14 ].…”

“…Similar results were also observed in women undergoing the first single fresh D5 blastocyst transfer. However, different opinions were held by other instigators as various confounders (such as the transfer of cleavage embryo or blastocysts, the number and quality of the transferred embryo, and the age and ethnicity of included women) influenced the reproductive outcomes [ 5 – 14 ]. For that reason, the aim of this study was to further evaluate the impact of preconception TSH levels between 2.5 and 4.2 mIU/L (which was used as the upper limit of the reference range in our laboratory) on reproductive outcomes in women undergoing their first fresh D3 embryo transfer.…”