Systematic Comparison of Short-Term Insemination and Conventional Insemination IVF: Influencing Factors, Embryo Developmental Quality and Pregnancy Outcomes

Abstract

In in vitro fertilization-embryo transfer (IVF-ET), the selection of insemination duration is a key variable affecting pregnancy outcomes. This paper systematically compares the differences between two insemination strategies, namely short-term insemination (4-6 hours) and conventional IVF (16-18 hours), in terms of influencing factors, embryo development and pregnancy outcomes, aiming to provide evidence-based basis for the selection of individualized insemination protocols. Studies have shown that the choice of insemination method should be based on a comprehensive assessment of patients’ clinical characteristics, oocyte status and sperm function parameters. Analysis of embryo development kinetics indicates that embryos from short-term insemination have more synchronous pronuclear formation and early cleavage, and a shorter time to blastocyst formation. However, there is no significant difference in the overall blastocyst formation rate and live birth rate between the two methods. By reducing the exposure time to reactive oxygen species, short-term insemination shows advantages in populations with high oxidative stress (such as polycystic ovary syndrome (PCOS) and oocytes derived from small follicles) and specific male factors (such as oligozoospermia and asthenospermia). It can improve fertilization rate, high-quality embryo rate and early pregnancy rate, and may reduce the risk of early miscarriage. In contrast, conventional insemination may be more conducive to embryo implantation and maintenance of continuous pregnancy in women with high oocyte maturity (MII rate > 80%) and advanced age (≥38 years old). Current studies have limitations such as insufficient standardization of laboratory procedures and high population heterogeneity. In the future, it is necessary to further clarify the optimal insemination strategy for different populations through unified operation standards, refined stratified studies and long-term follow-up, so as to promote the precision and individualization of IVF insemination protocols.