Prolonged TV viewing linked to lower sperm count

Men who do little exercise and spend much of their spare time watching TV have lower sperm counts than more active men, a study suggests.

Clocking up 20 hours a week of TV time appears to be detrimental, the US authors from Harvard say in the British Journal of Sports Medicine.

Yet 15 hours or more of exercise a week boosts semen quality, according to the results in nearly 200 college students.

The researchers said more studies were needed to explore the possible causes.

And some experts say men wanting to conceive need to be selective about the sport they do as some types may harm sperm.

Too much time riding a bike or doing long-distance running in tight clothing may not be good, other studies suggest.

Up to a fifth of young men find themselves with a low sperm count, defined as fewer than 20 million sperm per millilitre of semen.

A low sperm count or poor sperm quality is the cause of infertility in about 20% of couples with fertility problems in the UK, and a contributory factor in a further 25% of couples.

This page offers advice for people who think that they, or their partner, may have a low sperm count, known medically as oligozoospermia. It explains the causes of a low sperm count, how you get this problem properly diagnosed, and the treatment options available.

Getting diagnosed

If you have not managed to conceive after one year of trying for a baby, you should see your GP. They will be able to carry out fertility investigations including a semen test to check the quality and quantity of your (or your partner's) sperm.

About 1 in 10 men will have an abnormal result on the first semen test but this does not always mean they have a 'true' abnormality. So, if the results of the first semen test are abnormal, the test should be repeated.

Ideally, this repeat test should be done three months after the first, but if it looks as though your sperm count is very low or you have no sperm at all, it should be repeated as soon as possible.

Similarly, wearing tight underwear rather than boxer shorts has been linked with lower sperm levels.

Sedentary lifestyle

In the latest study, the researchers from the Harvard School of Public Health asked 189 young men who were students at a university in New York to record how many hours they had been spending doing physical activity and watching TV in a typical week.

The production of sperm is a complex process and requires normal functioning of the testicles (testes) as well as the hypothalamus and pituitary glands — organs in your brain that produce hormones that trigger sperm production. Once sperm are produced in the testicles, delicate tubes transport them until they mix with semen and are ejaculated out of the penis. Problems with any of these systems can affect sperm production. Also, there are problems of abnormal sperm shape (morphology) or movement (motility). Often the cause of low sperm count isn't ever identified.