Effect of abnormal semen parameters on ICSI: morphokinetics and cumulative clinical outcomes of 10,623 embryos

Does sperm quality influence embryo morphokinetics, embryo quality and reproductive outcomes in intracytoplasmic sperm injection (ICSI) cycles?

Retrospective cohort study (10,623 embryos from 1680 patients; 1836 ICSI cycles) conducted at a single IVF centre (2019-2023). Embryos were grouped by semen quality and origin: normozoospermia (n = 8799), severe oligozoospermia (n = 567), severe oligoasthenozoospermia (n = 716) and testicular sperm extraction (TESE) (n = 541). Time-lapse microscopy was used to assess morphokinetic parameters. Developmental and clinical outcomes were analysed for first and cumulative transfers.

A total of 14,568 oocytes were inseminated. Normal fertilization (two pronuclei) was highest in the normozoospermia group (74.6%) and declined progressively with impaired semen quality: oligozoospermia (69.4%), oligoasthenzooospermia (68.3%) and TESE group (59.6%) (all P ≤ 0.042 versus normozoospermia). Correspondingly, the proportion of non-fertilized oocytes increased as follows: normozoospermia (9.8%), oligozoospermia (15.7%), oligoasthenozoospermia (15.8%) and TESE (22.1%) (all P ≤ 0.012 versus normozoospermia). One-pronucleus zygotes were also more frequent in the TESE group (7.2%) compared with the normozoospermia group (4.8%) (P = 0.019). The TESE-derived embryos showed accelerated cleavage from pronuclear fading to the five-cell stage (P ≤ 0.027). Blastocyst quality was reduced in the TESE and severe oligoasthenozoospermia groups. First transfer outcomes were comparable across groups; cumulative implantation, pregnancy and live birth rates per embryo transferred were lower for TESE (P ≤ 0.031).

Semen origin significantly affects embryo development and cumulative outcomes in ICSI cycles. Although moderate impairments had limited effect, TESE-derived spermatozoa were associated with altered morphokinetics, poorer embryo quality and lower cumulative success rates. Sperm origin represents a clinically relevant factor for embryo evaluation and transfer decision-making.