Abstract
STUDY QUESTION: What are the impacts of different male infertility factors on embryological, cumulative pregnancy and neonatal outcomes of IVF/ICSI cycles? SUMMARY ANSWER: Some severe male infertility factors, i.e. severe oligoasthenozoospermia (OAT-S) and non-obstructive azoospermia (NOA), may be negatively associated with fertilization, embryo development, and cumulative live birth rates, but not with neonatal outcomes. WHAT IS KNOWN ALREADY: Previous studies examining the effect of male infertility factors on IVF/ICSI clinical outcomes have drawn contradictory conclusions, largely because the semen quality of male partners could fluctuate due to many factors, and there are many confounding factors from female partners. STUDY DESIGN SIZE DURATION: This retrospective cohort study involved 4714 males with various semen abnormalities and 10 283 males with normozoospermia whose partners underwent their first IVF/ICSI cycle between January 2018 and September 2022 in the reproductive medicine centre of a university hospital. PARTICIPANTS/MATERIALS SETTING METHODS: Only couples with infertility caused by fallopian tubal factors, male factors, or unknown reasons were included. The patients were divided into five different groups: normozoospermia (N), mild-moderate male factor (MMF), OAT-S, azoospermia-husband (Azoospermia-H), and azoospermia-donor (Azoospermia-D). The Azoospermia-H group was further divided into obstructive azoospermia (OA) and NOA. We compared rates of fertilization, embryo development, and cumulative pregnancy as well as neonatal outcomes. Reproductive and neonatal outcomes of men with various semen abnormalities were studied through propensity score matching (PSM) comparisons along with corresponding control groups (N) (with matching factors: female age, female BMI, male age, male BMI, ovarian stimulation protocol, number of oocytes obtained, and endometrial thickness). Fertilization outcomes were also compared and stratified by IVF or ICSI. MAIN RESULTS AND THE ROLE OF CHANCE: The mean female ages in the azoospermia, OAT-S, MMF, and N groups were 28.9, 29.4, 31.0, and 31.0 years old, respectively, which were similar between groups after PSM. The normal fertilization rates were significantly reduced in the OAT-S and Azoospermia-H groups compared with the control group in ICSI cycles (68.1% vs 71.5%, P = 0.001; 65.3% vs 72.4%, P < 0.001). The embryo utilization rates were also significantly decreased in the OAT-S and Azoospermia-H groups compared with controls in IVF/ICSI cycles (48.8% vs 57.3%, P < 0.001; 53.9% vs 58.1%, P = 0.001). Regarding pregnancy outcomes, the cumulative live birth rate in the OAT-S group was decreased (66.3% vs 74.5%, OR 0.68, 95% CI: 0.56-0.81). Among azoospermia cases, the NOA group exhibited a lower live birth rate (66.4% vs 75.8%, OR 0.63, 95% CI: 0.40-0.99), and an increased pregnancy loss rate (18.2% vs 9.4%, OR 2.15, 95% CI: 1.20-3.85) compared with the control group. No impact of male infertility factor on obstetrical/perinatal outcomes was observed. In IVF/ICSI cycles, reproductive and neonatal outcomes were similar between the MMF, Azoospermia-D, OA, and control groups. LIMITATIONS REASONS FOR CAUTION: The main limitation of this study was the observational and retrospective design itself. Despite covariate adjustment, residual bias remained, and the single-centre cohort limited its generalizability. WIDER IMPLICATIONS OF THE FINDINGS: These findings offer new insights for the OAT-S and NOA groups for whom interventions before IVF/ICSI could be encouraged. Reassuringly, IVF/ICSI may be an effective and safe method for patients in the MMF, Azoospermia-D, and OA groups, avoiding additional medical treatments and associated burdens. STUDY FUNDING COMPETING INTERESTS: This study was supported by grants from the National Key Research and Development Plan Fund (No. 2018YFA0108400). The funders had no role in the study design, data collection or analysis, publication decision, or manuscript preparation. The authors declare that they have no competing interests. TRIAL REGISTRATION NUMBER: N/A.