Marijuana Use in Young Men Disrupts the Size and Shape of Their Sperm

Fostering a love of marijuana may not be the best habit for anyone, but particularly for young men looking to start a family.

"If you're a cannabis user and you're trying for a baby ... stop," says Dr. Allan Pacey, senior lecturer in andrology at the University of Sheffield in the United Kingdom and lead study author of new research that re-links the notion of stoner fertility issues.

The study, published in the journal Human Reproduction, examined a young men's lifestyles and how weed affected the size and shape of their sperm. For this study in particular, researchers collected data from 1,970 men who provided sperm as part of a fertility assessment.

Based on settings defined by the World Health Organization (WHO), only 4 percent of the sample size produced "normal" sperm with correct shape and size, while 318 participants produced abnormal sperm. Men with the abnormal sperm were more likely to be under 30 and had used marijuana within the last three months of giving their sperm sample.

"Cannabis smoking was more common in those men who had sperm morphology less than 4%," Pacey says. "Cannabis affects one of the processes involved in determining size and shape. And we also know that the way cannabis is metabolized is different in fertile and infertile men."

The study findings also showed that various factors--including drug use, employment history, BMI, medical history and even the type of underwear the men wore--were not relevant indications of their fertility risks involving the drug.

The American Society for Reproductive Medicine adds that as a third of all infertility cases are because of issues with the male partner, families trying to conceive should not use marijuana. The drug's use is associated with impaired sperm count and other abnormalities, in some cases.