Intracytoplasmic Sperm Injection Versus In vitro Fertilization in Infertile Women with Thyroid Autoimmunity

Background: It has been reported that intracytoplasmic sperm injection (ICSI) may be the preferred fertilization method for women with thyroid autoimmunity (TAI) seeking assisted reproduction. We compared the reproductive outcomes of women with TAI who were treated with ICSI compared to in vitro fertilization (IVF). Methods: In this retrospective cohort study, we included women with infertility who were referred to the Reproductive Centre of Peking University Third Hospital for their first IVF/ICSI and embryo transfer treatment cycle from January, 2019 to February, 2021. In total, 2,171 and 743 women with TAI underwent IVF and ICSI, respectively, while 8,702 and 2,688 women without TAI underwent IVF and ICSI, respectively. We examined the cumulative live birth rate (primary outcome) from the initiated stimulative cycle as well as the secondary outcomes of fertilization rate, rates of clinical pregnancy and live birth after the first embryo transfer cycle. We compared the reproductive outcomes of women treated with IVF and ICSI according to TAI status. Multivariable logistic regression analyses were performed to adjust for relevant confounders. Results: Women who underwent ICSI had significantly higher fertilization rates than those who underwent IVF (median [interquartile range]: 0.6 [0.5-0.8] in TAI-positive and IVF group vs. 0.7 [0.5-0.8] in TAI-positive and ICSI group vs. 0.6 [0.5-0.8] in TAI-negative and IVF group vs. 0.7 [0.5-0.8] in TAI-positive and ICSI group, p<0.001). However, the rates of cumulative live births, clinical pregnancies, and live births were significantly lower among women with TAI who underwent ICSI than those who underwent IVF (cumulative live birth: 51.8% vs. 47%, adjusted odds ratio: 0.80, 95% CI: 0.67–0.97); clinical pregnancy: 43.0% vs. 38.8%, adjusted odds ratio: 0.81, 95% confidence interval [CI]: 0.67–0.97; live birth: 36.2% vs. 32.4%, adjusted odds ratio: 0.81, 95% CI: 0.66–0.98). Conclusion: We observed that the use of ICSI in women with TAI was not associated with better assisted reproductive outcomes compared to IVF. Further prospective clinical trials are needed to confirm our findings.