Objective. To evaluate the impact of preconceptional serum TSH levels on the clinical outcomes of infertile patients undergoing their first IUI treatment cycle. Method. This was a retrospective study. Euthyroid patients undergoing the first cycle of IUI treatment from Jan 2017 to Aug 2018 were included. The patients were divided into a normal high TSH level (2.5–4.0 mIU/L) group and a low TSH level (0.4–2.5 mIU/L) group. Then, different factors were included separately to compare the outcomes between normal high and low TSH levels. The primary outcomes were clinical pregnancy rates, implantation rates, and miscarriage rates. The secondary outcomes were obstetric outcomes such as single live birth rates, birth length, birth weight, and duration of gestation. Results. Initially, 1856 patients were included, and 371 patients were excluded for different reasons. A total of 1485 patients were finally included in the analysis. The general parameters between normal high and low TSH levels were similar except for infertile duration and female BMI, which were, however, significantly different between AID-IUI patients and AIH-IUI patients (P=0.005 and P=0016). No significant differences were found in terms of either primary outcomes or secondary outcomes. Conclusion. Normal high-serum TSH levels within the reference range (0.4–4.0 mIU/L) measured before treatment seemed to have no adverse impact on the clinical outcomes of patients undergoing their first IUI treatment cycle.

Purpose. To investigate the association between high-normal preconception TSH levels and reproductive outcomes in infertile women undergoing the first single fresh D5 blastocyst transfer. Methods. This was a retrospective study. Euthyroid patients undergoing the first single fresh D5 blastocyst transfer from January 2018 to May 2019 were initially included. The patients were divided into a low TSH (0.27–2.5 mIU/L) group and a high-normal TSH (2.5–4.2 mIU/L) group. The reproductive outcomes were compared between the groups. Results. A total of 824 women were ultimately included, 460 of whom had serum TSH levels less than 2.5 mIU/L and 364 of whom had serum TSH levels between 2.5 and 4.2 mIU/L. The patients were highly homogeneous in terms of general characteristics. High-normal TSH levels had no adverse impact on the clinical pregnancy rate, miscarriage rate, or live birth rate (respectively, aOR = 0.84, 0.65, 0.61, and P=0.234, 0.145, 0.083). No significant differences were observed in terms of gestational age, single live birth rates, birth weight, or birth length. Conclusion. High-normal TSH levels did not significantly influence reproductive outcomes in infertile women undergoing the first single fresh D5 blastocyst transfer. Further studies are needed to test whether the results might be applicable to a wider population.

Purpose. To investigate the association between high-normal preconception TSH levels and reproductive outcomes in infertile women undergoing the first fresh D3 embryo transfer. Methods. This was a retrospective study. Euthyroid patients undergoing the first fresh D3 embryo transfer from January 2018 to May 2019 were initially included. The patients were divided into a low-TSH (0.27–2.5 mIU/L) group and a high-normal TSH (2.5–4.2 Miu) group. The reproductive outcomes were compared between the groups. Results. A total of 1786 women were ultimately included, in which 1008 of whom had serum TSH levels between 0.27 and 2.5 mIU/L and 778 of whom had serum TSH levels between 2.5 and 4.2 mIU/L. The patients were highly homogeneous in terms of general characteristics. High-normal TSH levels had no adverse impact on the clinical pregnancy rate, miscarriage rate, or live birth rate (respectively, aOR = 0.92, 1.30, and 0.88 and P  = 0.416, 0.163, and 0.219). No significant differences were observed in terms of gestational age, single live birth rates, and birth weight, or birth length. Conclusion. High-normal TSH levels did not significantly influence reproductive outcomes in infertile women undergoing the first fresh D3 embryo transfer. Further studies are needed to test whether the results might be applicable to a wider population.

ObjectiveReproductive outcomes in euthyroid women with high‐normal thyroid‐stimulating hormone (TSH) levels are comparable to those in euthyroid women with low TSH levels; however, few studies have investigated whether strictly controlled TSH levels after levothyroxine (LT4) treatment impair reproductive outcomes in infertile women with subclinical hypothyroidism (SCH). This study aimed to investigate the impact of high‐normal versus low‐normal TSH levels on reproductive outcomes in women undergoing their first in vitro fertilisation and embryo transfer (IVF‐ET) cycle.DesignThis was a retrospective cohort study. Patients were divided into low‐normal (TSH < 2.5 mIU/L, and ≥0.27 mIU/L) and high‐normal (TSH ≥ 2.5 mIU/L, and <4.2 mIU/L) groups based on TSH levels after LT4 treatment. TSH levels after LT4 treatment and before ovarian stimulation were recorded. Reproductive outcomes were compared between the low‐normal and high‐normal TSH groups and between the euthyroid and LT4‐treated groups.ResultsA total of 6002 women, 548 of whom were LT4‐treated women, were finally included in this study. Among the LT4‐treated women, 129 women had low‐normal TSH levels, and 167 women had high‐normal TSH levels. The clinical pregnancy rate, miscarriage rate, and live birth rate were comparable between the low‐normal and high‐normal groups (all p > .05). When adjusted by age, anti‐Mullerian hormone (AMH) levels, infertility duration, transferred embryos, and dose and duration of LT4 treatment, high‐normal TSH levels neither significantly decreased miscarriage (adjusted odds ratio [aOR] = 2.27, 95% confidence interval [CI] = 0.77–6.69, p = .14) nor increased clinical pregnancy (aOR = 1.15, 95% CI = 0.70–1.89, p = .57 or live birth (aOR = 0.97, 95% CI = 0.60–1.59, p = .92). Similar obstetric outcomes were observed between the low‐normal and high‐normal TSH groups after LT4 treatment and between the euthyroid and LT4‐treated groups (all p ≥ .05).ConclusionsHigh‐normal TSH levels did not have adverse effects on clinical and obstetric outcomes when compared with low‐normal TSH levels after LT4 treatment. However, whether it is appropriate to set 2.5 mIU/L as the goal of treatment before IVF/ICSI remains to be determined in further well‐designed studies.