ABOUT THOSE SWIMMERS

About a third of infertility cases are attributed to sperm. Male fertility depends on three factors:

■ QUANTITY

A healthy, fertile man will have 20 million sperm per millimetre of semen. You’d think that a fraction of that number would be enough to do the trick, but amazingly, only 200 of that number reach the egg. Although you only need one successful sperm to get the job done, the fewer healthy sperm he has, the more difficult it is.

■ QUALITY

The sperm has an oval head and a long tail to propel it forwards. Fertility problems may occur if the sperm are of abnormal size or shape.

■ MOTILITY

The sperm has to wriggle and swim its way to the egg. Good sperm motility (movement) is important for impregnation.