A Study of Factors Affecting the Success of Human Fertilization in Vitro. II. Influence of Semen Quality and Oocyte Maturity on Fertilization and Cleavage

Abstract

The incidence of in vitro fertilization was analyzed with respect to the degree of cumulus dissociation (expansion) at the time of oocyte recovery and also the semen quality. Of the oocytes surrounded by perfectly (++) or moderately (+) dissociated cumuli, 78.6% and 30.8%, respectively, (P < 0.001), were fertilized when the husband''s semen analysis was in the normal range. The proportion of fertilized oocytes was not decreased in cases of polyzoospermia (> 130 .times. 106 spermatozoa/ml), but was decreased (P < 0.05) when the semen analysis revealed other anomalies: oligozoospermia (< 15 .times. 106 spermatozoa/ml), asthenozoospermia (< 50% motile cells) or teratozoospermia (> 50% abnormal spermatozoa). The proportion of fertilized eggs cleaving in vitro was unaffected by semen quality but was lower when + cumulus oocytes were collected than when ++ cumulus oocytes were obtained (58.3% vs. 87.0%, P < 0.02). In vitro incubation of the oocyte prior to insemination increased the incidence of fertilization by .apprx. 28% for both + (22.2 to 50.0%) and ++ (65.7 to 93.9%) cumulus oocytes. Finally, 67.6% of ++ cumulus oocytes developed into embryos when the insemination with spermatozoa from normal semen samples was delayed by several hours, compared with only 29.0% when the conditions were suboptimal (+ cumulus oocyte, abnormal semen analysis or no delay prior to insemination). Eight pregnancies began following the replacement of 38 embryos in 34 patients. Six spontaneous abortions occurred, and chromosomal abnormalities were proven in the 2 cases analyzed. Two pregnancies continued for more than 3 mo., resulting in term deliveries of 2 normal babies.