Effects of paternal metabolic factors on sperm quality and reproductive outcomes of intrauterine insemination

Guowei Du^1,#, Jianhuai Chen^2,#, Heng Wang³, Shanshan Chen¹, Yanting Wang¹, Jing Wang¹, Guangzhao Yang⁴, Siwen Liu^5,*, Xuanyi Chen^1,*
1 Department of Reproduction, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, China
2 Department of Andrology, Jiangsu Province Hospital of Chinese Medicine, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
3 Department of Urology, Suzhou Hospital, Xiyuan Hospital of China Academy of Chinese Medical Sciences, Suzhou, China
4 Department of Andrology, Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine, Suzhou, China
5 Department of Oncology, Jiangsu Cancer Hospital & Jiangsu Institute of Cancer Research & The Affiliated Cancer Hospital of Nanjing Medical University, Nanjing, China
* Corresponding Author: Siwen Liu. Email: email ; Xuanyi Chen. Email: email
# Guowei Du and Jianhuai Chen are co-first authors
(This article belongs to the Special Issue: Integrating Andrology into Reproductive Medicine: Challenges and Innovations in Male Infertility)

Canadian Journal of Urology https://doi.org/10.32604/cju.2026.079068

Received 14 January 2026; Accepted 01 June 2026; Published online 18 August 2026

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Abstract

Background: Elevated body mass index (BMI) often involves metabolic disturbances, which may influence sperm quality and intrauterine insemination (IUI) pregnancy success. Understanding the metabolic factors’ mediating role here is essential to clarify how elevated male BMI links to reproductive outcomes. Methods: This retrospective study included 220 couples undergoing IUI at Suzhou TCM Hospital Affiliated to Nanjing University of Chinese Medicine (July 2022 to December 2024). Male partners were stratified by BMI categories according to Chinese criteria. Baseline demographic, metabolic parameters (alanine aminotransferase [ALT], aspartate aminotransferase [AST], gamma-glutamyl transferase [GT], fasting plasma glucose [FPG], triglycerides [TG], total cholesterol [TC]), and semen parameters were collected. Clinical pregnancy and live birth rates were the primary outcomes. Multivariable logistic regression and structural equation modeling (SEM) were employed to assess independent associations and mediation effects. Results: Clinical pregnancy was achieved in 43 couples (19.5%). Male BMI was positively correlated with multiple metabolic markers (ALT, AST, GT, FPG, TG, TC; all p < 0.05). However, no significant differences in clinical pregnancy or live birth rates were observed across male BMI categories. SEM revealed a significant total indirect effect of male BMI on clinical pregnancy through ALT, TG, and processed total motile sperm count (PTMS) (β = −0.043, 95% confidence interval (CI): −0.080 to −0.007, p = 0.022), while the direct effect was non-significant (p = 0.456), indicating full mediation. PTMS (adjusted odds ratio [aOR] = 1.016, p = 0.001), normal sperm morphology (aOR = 1.141, p = 0.025), and sleep quality (Pittsburgh Sleep Quality Index [PSQI]; aOR = 0.746, p = 0.004) were independent predictors of clinical pregnancy. A significant indirect effect was also observed for preterm birth, though this analysis was limited by the small number of events. Conclusion: In this predominantly overweight cohort, elevated male BMI was associated with adverse metabolic profiles and poorer sperm quality, but BMI category alone did not significantly predict IUI success. Mediation analysis provides preliminary evidence that metabolic disturbances and reduced PTMS may serve as intermediate pathways linking higher male BMI to reproductive outcomes. Comprehensive preconception assessment of male partners, including metabolic screening and attention to modifiable lifestyle factors such as smoking cessation and sleep quality, may optimize reproductive success.