Successful human pregnancy following in vitro fertilization using frozen semen.

Frozen-thawed husband's semen was utilized for insemination of spouse's oocytes in vitro. Postthaw semen had a low motility (40%) with a poor forward progression (+2), which subsequently decreased rapidly in the regularly used Ham's F-10 medium (pH 7.42, 280 mosmol/kg) supplemented with 7.5% fetal cord serum. When Ham's F-10 was supplemented with an additional 0.5 mmol each of magnesium sulfate (MgSO4) and potassium bicarbonate (KHCO3) at a higher pH (pH 7.69, 280 mosmol/kg), the sperm maintained their motility and forward progression and fertilized all the oocytes, which subsequently cleaved and developed into normal embryos. Transfer of these embryos resulted in a normal pregnancy. Our results indicate that cryopreserved semen of poor quality can be successfully employed for an in vitro fertilization-embryo transfer (IVF-ET) program, especially when MgSO4 and KHCO3 are used in Ham's F-10 at a higher pH.