Monthly variation in human semen quality in male partners of infertile women in the tropics

The aim of the study was to determine whether there were significant 'seaso nal' variations in the rhythm of sperm parameters (i.e. semen volume and sp erm density) of men who reside in the tropics. A total of 7656 semen analys is results from the department of obstetrics and gynaecology of a tertiary general hospital was analysed. These samples were obtained as part of an in itial screening for male partners of couples with problems trying to concei ve who were attending a fertility clinic from 1991 to 1995. The subjects' m ean semen volume and sperm density of 2.9 ml and 26.9x10(6)/ml respectively were within the World Health Organization reference values. There were no significant month-to-month variations in the adjusted (for age of subject, year of test and technologist who performed the analysis by analysis of co- variance, ANCOVA) mean semen volume and sperm density over the 5 year perio d. Variations in semen volume and density observed in the temperate climate s are not seen in this study, which was conducted in subjects staying in th e tropics. This observation may be related to relative constant temperature and hours of light exposure among men who reside in the tropics. As this s tudy is, so far, published data from only one country, Singapore, it may no t truly reflect the actual situation for individuals who are residing in th e tropics.