(CBS News) Unhealthy habits may not have a factor in sperm count, according to a new study.
Scientists from the Universities of Manchester and Sheffield have discovered that lifestyle choices such as smoking or his weight may have no affect the number of swimming sperm a man has. Currently, organizations such as the National Institute for Clinical Excellence and the Mayo Clinic claim that "general health and lifestyle issues," such as poor nutrition, obesity or use of alcohol, tobacco and drugs could cause male infertility.
"This potentially overturns much of the current advice given to men about how they might improve their fertility and suggests that many common lifestyle risks may not be as important as we previously thought," Dr. Andrew Povey, from the University of Manchester's School of Community Based Medicine, said in the press release.
Reasons for male infertility can include abnormal sperm production or function, problems with sperm delivery, overexposure to environmental factors - including pesticides, chemicals or heat - and damage caused by cancer and cancer treatments, according to the Mayo Clinic.
For the study, 2,249 men from 14 fertility clinics around the United Kingdom completed detailed questionnaires about their lifestyle. Their answers were compared to 939 men who ejaculated low numbers of swimming sperm and a control group of 1,310 men who produced higher numbers. Fertility was determined by the number of swimming sperm men ejaculated.
Scientists found that men who ejaculated low numbers of swimming sperm were 2.5 times more likely to have had testicular surgery and twice as likely to be black. They were also 1.3 times more likely to be in manual work, not wear boxer shorts or not had a previous conception.
But, recreational drugs, tobacco and alcohol, and body mass index (BMI), had little correlation. The rate of men who had low numbers of swimming sperm who never smoked were about the same as the number of men who smoked 20 cigarettes a day and had low numbers.
Povey believes this research means that couples might not have to wait for men to make lifestyle changes such as losing weight or quitting smoking before going ahead and pursuing fertility treatment.
"Delaying fertility treatment then for these couples so that they can make changes to their lifestyles, for which there is little evidence of effectiveness, is unlikely to improve their chances of a conception and, indeed, might be prejudicial for couples with little time left to lose," he said.
Researchers point out that the study did not look at the size and shape of sperm, otherwise known as sperm morphology, or the quality of DNA - other factors that may cause infertility.
"It remains possible that they could correlate with other aspects of sperm that we have not measured," Dr. Allan Pacey, senior lecturer in Andrology at the University of Sheffield, said in the press release.
"In spite of our results, it's important that men continue to follow sensible health advice and watch their weight, stop smoking and drink alcohol within sensible limits. But there is no need for them to become monks just because they want to be a dad. Although if they are a fan of tight Y-fronts, then switching underpants to something a bit looser for a few months might be a good idea!" he added.
The research was published in Human Reproduction on June 12, 2012.