The heaviest men had a higher proportion of abnormal sperm, as well as other problems. The scientists told a European fertility conference losing weight probably boosted fertility. Being obese is already known to affect women's chances of getting pregnant. The men were divided into four groups, according to their BMI (body mass index). Other factors which could affect fertility, such as smoking, high alcohol use and age, were taken into account by the researchers. Men who had a healthy BMI of 20 to 25 were had higher levels of normal sperm than those who were heavier. They also had higher semen volume, the European Society for Human Reproduction and Embryology meeting in Barcelona was told. ---- Read more at : http://news.bbc.co.uk/1/hi/health/7494777.stm