Advanced paternal age has been overlooked, and its effect on fertility remains controversial. Previous studies have focused mainly on intracytoplasmic sperm injection (ICSI) cycles in men with oligozoospermia. However, few studies have reported on men with semen parameters within reference ranges. Therefore, we conducted a retrospective cohort study analyzing the reproductive outcomes of couples with non-male-factor infertility undergoing in vitro fertilization (IVF) cycles. In total, 381 cycles included were subgrouped according to paternal age (<35-year-old, 35–39-year-old, or ≥40-year-old), and maternal age was limited to under 35 years. Data on embryo quality and clinical outcomes were analyzed. The results showed that fertilization and high-quality embryo rates were not significantly different (all P > 0.05). The pregnancy rate was not significantly different in the 35–39-year-old group (42.0%; P > 0.05), but was significantly lower in the ≥40-year-old group (26.1%; P < 0.05) than that in the <35-year-old group (40.3%). Similarly, the implantation rate significantly decreased in the ≥40-year-old group (18.8%) compared with that in the <35-year-old group (31.1%) and 35–39-year-old group (30.0%) (both P < 0.05). The live birth rate (30.6%, 21.7%, and 19.6%) was not significantly different across the paternal age subgroups (<35-year-old, 35–39-year-old, and ≥40-year-old, respectively; all P > 0.05), but showed a declining trend. The miscarriage rate significantly increased in the 35–39-year-old group (44.8%) compared with that in the <35-year-old group (21.0%; P < 0.05). No abnormality in newborn birth weight was found. The results indicated that paternal age over 40 years is a key risk factor that influences the assisted reproductive technology success rate even with good semen parameters, although it has no impact on embryo development.

Keywords: embryo development; implantation; in vitro fertilization; paternal age; pregnancy; sperm

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