Does the wash-up and swim-up method of semen preparation play a role in sex selection?
Because of the higher built ratio of boys to girls (1.5 : 1) by in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT) at Tygerberg Hospital, the question arose as to whether the wash-up and swim-up method of semen preparation, used for our IVF procedure, plays a role in sex selection. Semen samples of 20 men were evaluated at different time intervals to determine the percentage of F-body-positive spermatozoa. It was found that the swim-up time affects the relationship between Y- and X-bearing spermatozoa, especially at time intervals of 30 and 45 min, where an optimum percentage of Y-bearing spermatozoa (p = 0.0039 and p = 0.0092, respectively) was found. Sperm obtained at these specific time intervals may influence the outcome of sex by IVF and GIFT in favor of males.