Short insemination during conventional in vitro fertilization increases embryo quality

Abstract Aim To compare clinical outcomes using short and long co‐incubation protocols in sibling oocytes based on embryo morphokinetic outcomes measured by time‐lapse incubator with stratification based on a woman's age and sperm quality. Design Our study included 72 cycles with >6 oocytes retrieved. Sibling oocytes were distributed for two parallel protocols: short (3 h; n = 421) or long (16–20 h; n = 434) insemination, using the same amount of spermatozoa from the same prepared sample. Oocytes were then washed and incubated for 5 days. Time‐lapse annotations of embryos were performed by experienced embryologists and artificial intelligence‐based Known Implantation Data scores for day 3 and day 5 were calculated with EmbryoScope software. Results Short‐insemination group exhibited a higher blastulation rate, better morphokinetic indicators, and higher Known Implantation Data scores on day 3 and day 5 of the utilized embryos. However, the fertilization rate and clinical pregnancy rate per embryo transfer did not differ between experimental groups. A higher rate of abnormal fertilization (>2 pronuclei) after long insemination was recorded in women under 35 years old or with a total motile sperm count above 5 million and above 40% motility after preparation. A higher rate of usable embryos was observed after short insemination with a total motile sperm count above 30 million before preparation or 5 million and over 40% motility after preparation. Conclusions Our results suggest that a short insemination protocol results in better embryo quality and should be considered as a favorable protocol, especially in young female patients or male patients with high sperm quality.