The diagnosis of male infertility—prospective time-specific study of conception rates related to seminal analysis and post-coital sperm—mucus penetration and survival in otherwise unexplained infertility

Abstract

Infertile women without any inherent female infertility factors and able to secrete normal cervical mucus were studied prospectively in relation to post-coital sperm—mucus penetration (PCT) and their partner's seminal analysis, excluding men with azoospermia. Time-specific cumulative conception rates calculated as for life-table analysis were related to each measured seminal variable on routine analysis of 2–3 samples (volume, density, proportion with progressive motility, and proportion with normal morphology); to various derivatives from combinations of these variables; to seminal findings after vital staining; and to the PCT results. The best seminal predictor of fertility was the motile normal sperm density (MNSD), the 18 month conception rates being 57.4% + 4.6 (SE) and 30.2% + 5.9 (ratio 1.9, P < 0.001) above and below a derived threshold value of 4 × 10⁶/ml. The PCT led to rates of 55.6% ± 4.3 and 14.9% ± 5.1 (ratio 3.73, P < 0.001) for positive and negative results, respectively. The PCT also gave rise to a significantly distinct intermediate poor-psitive sub-group (conception rate 30.6% ± 9.0). Seminal analysis (the MNSD) did not affect the conception rate associated with a positive PCT but helped to discriminate further with a negative PCT (conception rates 22.5% ± 8.7 with an MNSD above 4 × 10⁶/ml versus 5.6% ± 4.8 below, P < 0.05). The PCT was the single best predictor of fertility but seminal analysis (the MNSD) was of additional value after a negative PCT.