The prognosis of male subfertility: a survey of 1025 men referred to a fertility clinic.

A retrospective survey of 1025 consecutive men referred to a male fertility clinic was carried out: 180 (18%) produced a pregnancy while attending the clinic. There was an overall inverse relationship between age and the production of pregnancy, although the majority of pregnancies were in the partners of men aged 25 to 39 at referral. The proportion of pregnancies rose from 4% for men presenting with azoospermia to 27% for those with initial sperm counts of 11 to 20 million/ml. The relationship between production of pregnancy and sperm density was inconsistent for men with sperm densities above 20 million/ml. There was no significant difference in the sperm motility at referral between those who did or did not produce a pregnancy. Success was highest for men whose duration of infertility at referral was between 2 and 3 years. The importance of these findings to the investigation of infertile men is discussed.