Data collected by Boston University shows that fathers who smoke marijuana more frequently can increase a mother's chance of miscarrying.
Around 1,400 U.S. and Canadian couples were studied by the school of public health prior to their pregnancy for two months. When fathers smoked once a week or more, they found it doubled the mother's chance of miscarrying. If the father smoked less than once a week, there was no association with miscarriage.
Only 8% of the men smoked every week and 82% have never smoked. About 18% of couples reported a miscarriage. These miscarriages usually occurred within the first eight weeks of contraception.
There have been several studies conducted on the relationship between male fertility and marijuana and there's a lot of conflicting information.
According to one study, men who smoke marijuana at some point in their life have significantly higher concentrations of sperm than men who have never smoked marijuana. Another study concluded that men who smoke marijuana frequently have significantly less seminal fluid, a lower total sperm count and their sperm behave abnormally.
The research conducted by Boston University is set to be presented today in Philadelphia at the annual meeting of the American Society for Reproductive Medicine and still needs to be peer-reviewed. Until then, the data is still considered preliminary.