Sperm count and motility influence the results of human fertilization in vitro

In order to select sperm characteristics that can predict the outcome of in-vitro fertilization-embryo transfer (IVF-ET), semen samples delivered in conjunction with this treatment were studied carefully. We have analysed these data retrospectively in relation to the outcome of treatment. Ninety-one couples were treated for tubal infertility by IVF-ET. Fifteen women became pregnant. Sperm were isolated from semen using a swim-up technique and in most cases 40-80 x 10(3) (range 20-120 x 10(3)) motile sperm per ovum were used for insemination. The couples were divided into three groups: group A who achieved pregnancies, group B who achieved cleaved ova but no pregnancies, and group C who achieved no ova that were cleaved 48 h after oocyte recovery. Comparisons between these groups showed that some characteristics of the native semen samples and the swim-up preparations were significantly different: the sperm concentration (P = 0.001) and total sperm count (P = 0.003) in the native sample, the number of sperm recovered during 30 min of swim-up (P = 0.001), and the specific progressive motility of sperm in the swim-up preparation, both at the time of insemination and on each day, up to 5 days thereafter (P = 0.002-0.028). No pregnancy was achieved with a sperm concentration below 26 x 10(6) ml-1 in the native sample. Some of the sperm characteristics studied in this paper may be of value in the pretreatment evaluation for IVF treatment.