While the findings are certainly intriguing, it's important to note, as the researchers do, that the study is not without its limitations, and the results certainly don't mean that marijuana is great for your reproductive health - previous research has linked it to reduced fertility, after all.
In measuring the survey results with the semen sample analysis, the scientists found that those using marijuana tended to have higher sperm concentrations and counts than those who never smoked it.
"An equally important limitation is the fact that most of the data were collected while cannabis was illegal in MA, so it is hard to know to what extent men may have under-reported use of cannabis because of social stigma or potential consequences related to insurance coverage for infertility services", he said.
They reckoned that there could be a "non-casual explanation" to the effect of male testosterone on "sperm count and risk-taking behaviours". Among men who never smoked marijuana, 12 percent had lower-than-normal sperm concentrations.
None of these limitations or considerations invalidate study's findings, it's just a sign, as Chavarro said, that we need to study cannabis more (the fact that cannabis is still considered more risky than opioids by the USA government remains a roadblock to that research, incidentally).More news: RBI May Change Stance To "Neutral" In Shaktikanta Das's First Review
"We spent a good two months redoing everything, making sure that there wasn't any error in the data", Dr. Jorge Chavarro, lead author of the new study and an associate professor of nutrition and epidemiology, told Time.
However, Chavarro noted that some of those past studies surveyed men who use multiple drugs at once, making it hard to pinpoint the effects of marijuana alone.
Additionally, the hormone levels of these men were also different.
The study also found that among the men who had ever smoked pot, "those who smoked it more often had testosterone levels an average of eight nanograms per decilitre higher than those who used it less often".
In short, Allan Pacey meant high testosterone = risk-taking behaviours, like smoking weed. Second, because the study's sampling wasn't diverse - 88% of the men were Caucasian, 84% were college educated, and the average age was 36.3 years old - the results may not apply to the general population.More news: Eden Hazard to tell Chelsea he wants Real Madrid move
Given the illegal status of marijuana in some places and its social stigma, the researchers also have reason to believe some of the participants they studied underreported their marijuana use in the surveys.
Other experts in the field have questioned how robust the association is.
She said: "Our findings were contrary to what we hypothesised at the start of the study".
Numerous older studies had focused on animal models or had examined men with histories of drug abuse. However, they were shocked to find that those who smoked the drug - even if it was only once - had a higher fertility rate than those who did not.
Experts looked at the effect of smoking an average of two joints a week among 662 sub-fertile men in Boston, Massachusetts.More news: Trump Officially Picks Conservative For World Bank Head
A normal sperm count is at least 15 million/mL, according to the World Health Organization.