Twenty-year-old men have worse sperm quality than men of 60, according to a new Danish report.

Professor Jens Bonde, of the University of Arhus, believes it’s because more women now smoke during pregnancy.

In a study of 1,000 men of all ages, Professor Bonde and his team found that, on average, younger men had lower quality sperm.

The average 20-year-old had half as many sperm as the average 60-year-old, and many of the younger men were close to infertile, he said.

Professor Bonde told the Expressen newspaper: “One explanation is that more and more woman are heavy smokers. We need more and better studies of how the foetus is affected during pregnancy.”

More here.