Comparisons of conventional in vitro fertilization versus intracytoplasmic sperm injection in women with thyroid autoimmunity and non-male factor infertility, a propensity score matching analysis

The aim of the study is to compare the outcomes between the insemination methods of conventional in vitro fertilization and intracytoplasmic sperm injection in infertile women with thyroid autoimmunity and non-male factor infertility. This was a retrospective cohort study which included women with thyroid autoimmunity and non-male factor infertility. Reproductive outcomes such as embryo development parameters and clinical outcomes were compared between the two groups. The propensity score matching was applied to balance the general characteristics with significant differences between the two groups. Generalized estimating equations were used to explore the impact of ICSI on the embryo development potential of the inseminated oocytes. Sensitivity analysis using E-values was used to account for unknown confounders. After 1:2 propensity score matching, the general characteristics were all comparable. The good cleavage embryo rate, blastocyst utilization rate, and good blastocyst rate were significantly lower in the intracytoplasmic sperm injection group than those in the conventional in vitro fertilization group. After controlling for the confounding factors, intracytoplasmic sperm injection was significantly negatively associated with development of usable blastocysts and good blastocysts, while showed no impact on fertilized oocytes, usable cleavage embryos and good cleavage embryos. Although limited by the limited sample size, there were comparable clinical and obstetrical outcomes between conventional in vitro fertilization and intracytoplasmic sperm injection groups. Intracytoplasmic sperm injection neither improved the embryo development potential nor increased the clinical pregnancy and live birth rates compared to conventional in vitro fertilization in the studied population. Prospective studies that randomly divide the studied population in two the two groups and compare the reproductive outcomes are warranted.