The importance of employing stringent methods to recruit fertile male controls

Abstract

Two methods of recruiting fertile male controls were evaluated and compared. The first group was recruited from the partners of women attending an antenatal clinic without obtaining details of their reproductive history. The second group was recruited after obtaining a detailed reproductive history from the couple and employing stringent entry criteria. Entry criteria for the second group included a length of exposure to the risk of pregnancy of not more than 12 months and no previous episode of involuntary infertility for either partner. There were significant differences between the distributions of semen parameters obtained from the two groups, indicating that the selection criteria for "fertile" men significantly influence results obtained and therefore that it is important to employ stringent criteria for the recruitment of fertile male controls. The group which was recruited by stringent criteria (mean length of exposure to the risk of pregnancy of 3 months) was characterised by a significantly higher median concentration of spermatozoa which exhibited slow linear or nonlinear motility. This confirms the findings of a previous study which suggested that slow linear or nonlinear motility are superior forms of spermatozoal motion.

Temporal trends in sperm count: a systematic review and meta-regression analysis

“…Of the 244 estimates, 110 (45%) were Unselected Western, 65 (27%) Fertile Western, 30 (12%) Unselected Other and 39 (16%) Fertile Other. Data from the 185 publications included in the meta-analysis are available upon requestcontact corresponding author for access (Abyholm, 1981;Fariss et al, 1981;Leto and Frensilli, 1981; Wyrobek et al, 1981a,b;Aitken et al, 1982;Nieschlag et al, 1982;Obwaka et al, 1982;Albertsen et al, 1983;Fowler and Mariano, 1983;Sultan Sheriff, 1983;Wickings et al, 1983;Asch et al, 1984;de Castro and Mastrorocco, 1984;Fredricsson and Sennerstam, 1984;Freischem et al, 1984;Ward et al, 1984;Ayers et al, 1985;Heussner et al, 1985;Rosenberg et al, 1985;Aribarg et al, 1986;Comhaire et al, 1987;Kirei, 1987;Giblin et al, 1988;Kjaergaard et al, 1988;Mieusset et al, 1988Mieusset et al, , 1995Jockenhovel et al, 1989;Sobowale and Akiwumi, 1989;Svanborg et al, 1989;Zhong et al, 1990;Culasso et al, 1991;Dunphy et al, 1991;Gottlieb et al, 1991;Nnatu et al, 1991;Pangkahila, 1991;Weidner et al, 1991;Levine et al, 1992;Sheriff and Legnain, 1992;Ali et al, 1993;…”