Fittest sperm passes the fertility test

The sperm kingdom too follows the law of survival of the fittest, and the "handsome" sperm has the best chances of contributing to conception, according to research published in the New England Journal of Medicine. The new research suggests that the chances of conception depend not only on the number of sperm per millilitre of semen, but also their shape, size and motility. The sperms that are shaped closest to the ideal (i.e. have an oval head and a whippy tail rather than an enlarged, round head and shrivelled up tail) have greater chances of being able to fertilise the egg than others. The researchers studied 765 infertile men and 696 fertile men between the ages of 20 and 55 years. Semen samples were collected from the participants twice at an interval of 16 days. The samples were then tested for the number, motility and shape of the sperms. The results of the study indicated that men whose sperm samples had more than 48 million sperms per ml of semen out of which at least 63% were moving and at least 12% were close to the normal in shape, were most likely to be able to have children. The men who had less than 13 million sperms/ml, a motility of less than 32% or fewer than 9% normal shaped sperms, were identified as 'subfertile', i.e. with a diminished capability for successful fertilisation. The current WHO standards classify semen as normal if it contains more than 20 million sperm per ml and 50% of them are motile. The current study refrains from terming semen as "normal" or "abnormal". It rather focuses on the range of potency of semen. Infertility is a fairly common problem with one in six couples having a problem conceiving. In about half of the infertility cases, it is the man who is the infertile partner. Researches like this provide more insight into the nature of sperm that may be of particular use in modifying treatment for infertility. The secret of life, after all, lies in these miniscule carriers of genes.

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