Pregnancy from in vitro fertilization of human eggs after separation of motile spermatozoa by density gradient centrifugation.

The spermatozoa of infertile men, previously found to have poor fertilizing capacity in an in vitro system, were fractionated on discontinuous gradients of Percoll (Pharmacia Laboratories, Piscataway, NJ) and were used for insemination of human oocytes in an in vitro fertilization and embryo replacement program. Three of the five patients in the study had established ongoing pregnancies, including one patient with a triplet pregnancy from four transferred embryos. However, the other two patients continued to have poor fertilizing capacity with their husband's Percoll-separated spermatozoa.