New Study Shows Marijuana Affects Sperm Size, Shape & Quality

A new study has shown that smoking marijuana could cause infertility in males as it affects sperm quality and production.

In a study published in the medical journal Human Reproduction, researchers analyzed many different lifestyle factors that could possibly have an impact on male infertility.

The study was the largest of its kind, examining how habits such as smoking and drinking alcohol affected men’s sperm size and shape – also known as sperm morphology.

Reliable sperm morphology data was only available for 1,970 of the men recruited, and of this group, 1,652 men produced “normal” samples of sperm – meaning over 4 percent of their sperm was the right shape size. The other 318 men had abnormal samples, meaning less than 4 percent of their sperm morphology was correct.

When cross analyzing the sperm samples with the men’s lifestyle habits and other factors, the researchers found only two strong correlations. The men with abnormal sperm samples were nearly twice as likely to have ejaculated during the summer months (from June to August), and they were much more likely to have abnormal sperm if they had smoked cannabis in the three months prior to ejaculating.

“I do know there is some work in laboratory animals that suggests [marijuana] can affect the way the DNA in the sperm is packaged together, and that’s significant,” Dr. Alan Pacey, senior lecturer in andrology at the University of Sheffield in England, said. “When sperm are made, the DNA they maintain has to be packaged in the head very tightly, and when that process doesn’t work properly, you get an abnormal sperm. So the cannabis is maybe interrupting that DNA folding.”