A new report suggests more than 2.5 million men in Britain could have low fertility. The research by Norwich Union Healthcare estimates that 9% of the UK's 28.5 million men might have difficulty conceiving.

Many doctors blame smoking and alcohol for the trend.

Nearly half (44%) of the doctor's surveyed said smoking was the overwhelming main contributing factor to low male fertility. One in 10 (11%) blamed alcohol and 7% blamed stress.

Dr. Ann Robinson says, "The results of this survey are shocking and should be a wake-up call to men and women that drinking and smoking too much not only gives you a bad headache in the morning but can affect your ability to start a family."