Short insemination during conventional in vitro fertilization increases embryo quality.

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.