Effect of increased male body mass index (BMI) on semen quality andIVF-ET clinical outcomes

Background: This study aimed to determine how elevated male body mass index (BMI) influences semen characteristics, embryo quality during in vitro fertilization-embryo transfer (IVF-ET), and subsequent reproductive outcomes in infertile couples. Methods: We retrospectively collected and analyzed clinical records from all couples who underwent IVF-ET at our center between January 2022 and September 2025. The study included couples infertile for one year with normal karyotypes and excluded those using donor sperm, with major lifestyle/medical issues, or specific male reproductive disorders. Based on BMI classification standards for Chinese adults, participants were divided into a group of normally weight, overweight, and obese men. A total of 243 IVF-ET cycles (81 randomly selected per BMI group) were analyzed for semen parameters, embryo quality, and clinical outcomes; group differences were assessed using the Kruskal-Wallis (H statistic) for continuous data vs. χ2 tests for categorical outcomes. Results: It was only observed that significant differences were identified in male sperm progressive motility (H = 7.203, p = 0.027), total sperm motility (H = 8.173, p = 0.017) among the three BMI groups (p < 0.05). It was observed that significant differences were identified in miscarriage rate (χ2 = 11.383, p = 0.003), live birth rate (χ2 = 6.045, p = 0.049) among the three BMI groups (p < 0.05). Conclusions: These findings indicate that increased male BMI has a detrimental effect on sperm progressive motility and may adversely influence the clinical outcomes of assisted reproductive treatment.