Oligoasthenozoospermia is not associated with spontaneous abortions following in vivo pregnancies contrasting with in vitro fertilization data.

Previous data showed an association between low motile density (< 10 million motile/mL) and spontaneous abortion (SAB) following in vitro fertilization-embryo transfer (IVF-ET). The purpose of this study was to determine if the same association existed following intrauterine insemination (IUI). A retrospective review of IUI pregnancies was conducted. Patients with antisperm antibodies, a low hypo-osmotic swelling (HOS) test score (< 50%), or those using donor sperm were excluded. A total of 52 couples were enrolled in the study: 34 in the normal motile density (MD) group and 18 in the low MD group. The SAB rate in the normal group was 29.4% and in the low group was 27.8%. Thus, these data fail to corroborate the conclusions reached after evaluation of IVF pregnancies that low MD is a cause of SAB. However, since there is a large difference in the number of sperm that come in contact with the oocyte following IVF versus IUI, it may be that the implantation defect is not evident until the oocyte is exposed to a certain number of abnormal sperm.