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Background: Studies have shown that thyroid autoimmunity (TAI) is associated with increased risks of adverse pregnancy outcomes. The aim of this study was to investigate the associations between TAI and embryo quality in euthyroid women undergoing in vitro fertilization or intracytoplasmic sperm injection (IVF/ICSI). Methods: This retrospective cohort study included euthyroid infertile women with and without TAI (defined as a serum thyroperoxidase concentration ≥34 IU/mL or a thyroglobulin concentration ≥115.0 IU/mL) who underwent their first complete IVF/ICSI treatment cycles at a tertiary referral center between April 2016 and February 2022. Embryo quality measurements and clinical outcomes were compared between women with (TAI positive) and without TAI (TAI negative). The high-quality cleavage embryo rate and cumulative live birth rate (cLBR) were the primary outcomes. Results: A total of 499 TAI-positive and 2945 TAI-negative women were included in this study, and their mean (standard deviation) ages were 31.6 (4.5) and 30.9 (4.4) years, respectively (p = 0.001). The overall analysis showed no significant differences between TAI-negative and TAI-positive women in the high-quality cleavage embryo rate (n/N: 11,139/22,553 vs. 1971/3820; adjusted rate: 52.8% vs. 53.4%, p = 0.66) and cLBR (1917/2945 vs. 327/499; 53.4% vs. 56.2%, p = 0.31). Moreover, no significant differences were observed between TAI-negative and TAI-positive women in the rates of oocyte retrieval (35,078/51,978 vs. 5853/8628; 69.1% vs. 69.4%; p = 0.65), fertilization (23,067/34,197 vs. 3902/5728; 61.1% vs. 62.2%, p = 0.34), embryo utilization (18,233/22,553 vs. 3156/3820; 80.2% vs. 80.8%, p = 0.61), blastocyst formation (7051/13,721 vs. 1192/2330; 48.5% vs. 48.4%, p = 0.97), and high-quality blastocysts (4819/13,721 vs. 799/2330; 29.9% vs. 29.4%, p = 0.73). Furthermore, no significant differences were observed between TAI-negative and TAI-positive women in the clinical pregnancy rate (1524/2808 vs. 248/482; 46.7% vs. 44.6%, p = 0.40), early pregnancy loss rate (156/1524 vs. 23/248; 13.5% vs. 11.5%, p = 0.44), and LBR (1338/2808 vs. 218/482; 37.4% vs. 36.0%, p = 0.55) of the first transfer cycle. Conclusions: This study demonstrated that TAI in women was not associated with embryo quality or the cLBR following IVF/ICSI. Future large studies are warranted to confirm these findings. [ABSTRACT FROM AUTHOR]

Background: A recent study showed that paternal subclinical hypothyroidism adversely affects the clinical outcomes of assisted reproductive technologies (ARTs). The aim of this study was to determine whether paternal serum-free thyroxine (fT4) concentrations within the reference range are associated with ART outcomes. Methods: This retrospective cohort study included 4066 couples who received 4894 ART treatment cycles in our clinic between April 1, 2016 and August 31, 2021. The differences in sperm parameters and ART outcomes across the paternal fT4 concentration tertiles were compared by using generalized linear models or generalized estimation equation models. The primary outcomes were clinical pregnancy rate (CPR) and live birth rate (LBR) per oocyte retrieval after the first embryo transfer cycle. Results: The mean ages of the males and their female partners were 32.8 (standard deviation, 5.0) and 30.7 (standard deviation, 4.1) years, respectively. No significant differences were observed in the sperm parameters or ART outcomes between the paternal fT4 concentration tertiles of the overall population. However, a stratified analysis of men aged ≥35 showed an adjusted CPR of 0.36 [confidence interval, CI: 0.27–0.45] for the lower paternal fT4 concentration tertile relative to the middle (adjusted rate: 0.45, CI: 0.38–0.53) and upper (adjusted rate: 0.43, CI: 0.36–0.51) tertiles (p for trend >0.05). The adjusted LBRs were 0.21 [CI: 0.15–0.30] for men aged ≥35 in the lower fT4 concentration tertile (p = 0.024, with reference to the upper tertile), 0.27 [CI: 0.21–0.35] for those in the middle tertile, and 0.30 [CI: 0.23–0.38] for those in the upper tertile. No differences in these outcomes were observed in men aged <35. The nonlinear smoothing curve obtained by using fT4 concentration as a continuous variable further supported these findings. Conclusions: Men of older reproductive age (≥35 years old) with low-normal fT4 concentrations within the reference range are associated with a decreased LBR. Future prospective studies are warranted to confirm the detrimental effects of low-normal paternal fT4 concentrations on ART outcomes. [ABSTRACT FROM AUTHOR]

Background: Maternal subclinical hypothyroidism (SCH) is a risk factor for adverse pregnancy outcomes. However, it is still unclear whether SCH affects male fertility. The aim of this study was to determine the association between paternal SCH and clinical outcomes after in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). Methods: This retrospective study included 2511 couples with paternal euthyroidism (n = 2282) or SCH (n = 229) who visited our clinic for infertility treatment between April 1, 2017, and September 30, 2019. The primary outcomes were the fertilization rate and clinical pregnancy rate; the secondary outcomes were the good-quality embryo rate, blastocyst formation rate, implantation rate, and early miscarriage rate. These outcomes were compared between the euthyroid and the SCH groups after adjusting for various potential confounders. Results: The mean paternal ages in the euthyroid and SCH groups were 34.5 and 36.0 years, respectively (p = 0.002). Semen parameters and sperm DNA fragmentation index were similar between the two groups (all p > 0.05). The adjusted fertilization (0.69 vs. 0.71, p = 0.30), good-quality embryo (0.49 vs. 0.52, p = 0.31), blastocyst formation (0.51 vs. 0.53, p = 0.57), and early miscarriage (0.11 vs. 0.10, p = 0.81) rates were also similar between the two groups. There was a significantly decreased adjusted clinical pregnancy rate [confidence interval, CI] and implantation rate [CI] in the paternal SCH group compared with the euthyroid group (0.32 [0.26–0.40] vs. 0.42 [0.40–0.45], p = 0.009 for the clinical pregnancy rate; 0.24 [0.19–0.29] vs. 0.29 [0.27–0.31], p = 0.037 for the implantation rate). Stratified analysis indicated that these differences were only significant in men aged ≥35 years (p = 0.009 and 0.022, respectively) and not in men <35 years (p = 0.39 and 0.45, respectively). Conclusions: Paternal SCH was associated with worse clinical outcomes after IVF/ICSI, whereas this detrimental impact was only present in males ≥35 years old. Prospective studies and basic research are warranted to confirm these results and to clarify the mechanisms underlying these associations, respectively. [ABSTRACT FROM AUTHOR]

Background: Overt thyroid diseases have been identified as risk factors for female infertility. However, it remains largely unclear whether subclinical hypothyroidism (SCH), a very common thyroid disorder, is associated with female infertility. This study aimed to investigate the potential association between SCH and the ovarian reserve in women seeking infertility treatment. Methods: This retrospective study included 2568 women with normal thyroid function (n = 2279) or SCH (n = 289) who visited our clinic for infertility treatment. Ovarian reserve markers, including follicle-stimulating hormone (FSH) concentrations on days 2–4, the antral follicle count (AFC), and anti-Müllerian hormone (AMH) concentration, were compared between euthyroid women and those with SCH. Multiple linear and Poisson regression analyses were used to estimate the associations of SCH with ovarian reserve markers. These analyses were repeated separately in women aged <35 (n = 1349) and ≥35 years (n = 1219). Results: In the total study population, women with SCH had significantly lower AMH concentrations (median: 2.05 vs. 2.51 ng/mL, p = 0.015) and AFCs (median: 10.0 vs. 11.0, p = 0.013), compared with euthyroid women. In linear and Poisson regression analyses, SCH was significantly associated with a higher basal FSH concentration (mean difference = 1.13 mIU/mL [95% confidence interval (CI) 0.97 to 1.29 mIU/mL], p < 0.001), lower AMH concentration (mean difference = −0.27 ng/mL [CI −0.43 to −0.12 ng/mL], p = 0.001), and lower AFC (mean difference = −0.7 [CI −1.3 to −0.2], p = 0.005). In women aged ≥35 years, SCH was significantly associated with FSH (mean difference = 1.74 mIU/mL, p < 0.001) and AMH concentrations (mean difference = −0.40 mg/mL, p < 0.001) and AFC (mean difference = −0.8, p < 0.001). In women <35 years old, SCH was significantly associated with a higher FSH concentration (mean difference = 0.30 mIU/mL, p < 0.001), but not with AMH or AFC concentrations (p = 0.84 and 0.06, respectively). Thyroperoxidase antibody (TPOAb) positivity was not associated with measures of ovarian reserve. Conclusions: The data suggest that SCH is associated with decreased ovarian reserve during later reproductive age. TPOAb positivity was not associated with ovarian reserve. Future research is necessary to investigate the underlying molecular mechanisms regulating the diminished ovarian reserve in women with SCH and to evaluate whether levothyroxine supplementation may improve the ovarian function of women with SCH. [ABSTRACT FROM AUTHOR]