The impact of paternal body mass index on semen parameters and assisted reproductive outcomes in couples undergoing IVF/ICSI-ET treatment.

Purpose: To investigate the impact of paternal body mass index (BMI) on semen parameters and assisted reproductive outcomes in couples undergoing their first IVF/ICSI-ET cycle.

Materials and methods: This retrospective study included 7618 couples undergoing IVF/ICSI-ET for maternal tubal/pelvic factors from 2017 to 2023. Paternal BMI was classified according to WHO criteria: normal weight (n = 3433), overweight (n = 3248), and obese (n = 937). Semen quality, embryological outcomes (utilizable/high-quality embryos, blastocysts), and ART outcomes (pregnancy, singleton live birth) were compared. ANOVA, chi-square tests, and multivariate regression were used; subgroup analyses were conducted for IVF and ICSI-ET.

Results: Normal sperm morphology was higher in the normal weight group (5.32 ± 4.92 %) vs. overweight (4.85 ± 3.53 %) and obese (4.79 ± 4.93 %) (P < 0.001). Utilizable embryo rate was higher in the normal weight group (84.22 ± 19.29 %) than in the overweight group (82.98 ± 20.20 %) (P = 0.018). The utilizable blastocyst rate was also higher vs. obese group (29.60 ± 22.61 % vs. 26.93 ± 21.87 %; P = 0.004). Clinical pregnancy rates were 59.2 %, 56.6 %, and 55.5 % in the normal, overweight, and obese groups, respectively (P = 0.037). ICSI subgroup showed limited ART differences except higher birthweight in the obese group (P = 0.003).

Conclusions: Men with normal BMI demonstrated better sperm morphology, embryo utilization, and pregnancy rates. These findings underscore the importance of assessing paternal BMI in ART and support integrating paternal weight management into preconception care.