高年齢妊産婦における子宮内授精成功率の向上：連続射精および最適化された周期パラメータの影響

This study evaluated whether consecutive ejaculate (CE) strategies improve intrauterine insemination (IUI) live birth rates (LBR) in women over 35 with unexplained or male-factor infertility. It also examined the influence of follicle number and sperm count thresholds on outcomes.

In this retrospective cohort study (2010-2019), 596 IUI cycles were analysed in 263 nulliparous women-230 with CE and 366 with standard IUI. Among them, 98 patients underwent CE IUI and 165 received non-CE IUI. Patients with total motile sperm count (TMSC) <5×106 were often fast-tracked to IVF, but CE was mostly attempted to boost sperm count beforehand. LBRs per cycle and per woman were compared between groups.

LBR per cycle was 11.3% (CE) vs. 13.1% (control) (p=0.52); per woman, 26.5% (CE) vs. 29.1% (control) (p=0.65). Mean ages were similar (37.7 vs. 38.0 years; p=0.34). Success improved with TMSC >10×106; 65.4% (CE) and 87.5% (control). Over six cycles, LBR rose from 10.5% to 13.8% (CE) and 12.3% to 16.7% (control). Outcomes improved with two or three follicles, especially in women over 35.

CE IUI yields LBRs comparable to standard IUI and may offer a cost-effective, less invasive alternative to IVF for male-factor infertility in women over 35. The LBRs per woman undergoing IUI were of a similar magnitude to those reported in IVF cycles. Optimising IUI LBR may involve increasing follicle numbers and using a higher TMSC threshold (>10×106). CE IUI supports healthcare sustainability while expanding fertility treatment access.