A first prospective study of the individual straight line velocity of the spermatozoon and its influences on the fertilization rate after intracytoplasmic sperm injection.

fertilization rate (84%) was significantly (P < 0.008) higher in the quartile of the sperm population with the highest VSL compared to the fertilization rate (68%) in the quartile with the lowest VSL. Embryo cleavage and embryo quality were not different in the quartiles of the sperm population used for injection.