Marijuana smoking linked with higher sperm concentrations, study finds

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Men who have smoked marijuana at some point in their life had significantly higher concentrations of sperm when compared with men who have never smoked marijuana, according to new research led by Harvard T.H. Chan School of Public Health. The study, conducted in the Fertility Clinic at Massachusetts General Hospital, also found that there was no significant difference in sperm concentrations between current and former marijuana smokers.

"These unexpected findings highlight how little we know about the reproductive health effects of , and in fact of the health effects of marijuana in general," said Jorge Chavarro, associate professor of nutrition and epidemiology at Harvard Chan School. "Our results need to be interpreted with caution and they highlight the need to further study the health effects of marijuana use."

The study will be published on February 5, 2019 in Human Reproduction.

It is estimated that 16.5% of adults in the U.S. use marijuana, and support for legal recreational use of marijuana has increased dramatically in recent years. Understanding the health effects associated with marijuana use is important given the growing perception that it poses few health hazards.

The researchers hypothesized that marijuana smoking would be associated with worse semen quality. Previous studies on marijuana have suggested that it is associated with negative effects on male reproductive health, but most of those studies had focused on animal models or on men with histories of drug abuse.

For this study, researchers collected 1,143 semen samples from 662 men between 2000 and 2017. On average, the men were 36 years old, and most were white and college educated. Additionally, 317 of the participants provided blood samples that were analyzed for reproductive hormones. To gather information on marijuana use among , researchers used a self-reported questionnaire that asked the men a number of questions about their usage, including if they had ever smoked more than two joints or the equivalent amount of marijuana in their life and if they were current marijuana smokers.

Among the participants, 365, or 55%, reported having smoked marijuana at some point. Of those, 44% said they were past marijuana smokers and 11% classified themselves as current smokers.

Analysis of the semen samples showed that men who had smoked marijuana had average sperm concentrations of 62.7 million sperm per milliliter of ejaculate while men who had never smoked marijuana had average concentrations of 45.4 million sperm per milliliter of ejaculate. Only 5% of marijuana smokers had sperm concentrations below 15 million/mL (the World Health Organization's threshold for "normal" levels) compared with 12% of men who had never smoked marijuana.

The study also found that among marijuana smokers, greater use was associated with higher serum testosterone levels.

The researchers cautioned that there are several potential limitations to the findings, including that participants may have underreported marijuana use given its status as an illegal drug for most of the study period. The researchers emphasized that they do not know to what extent these findings may apply to men in the as the study population consisted of subfertile men in couples seeking treatment at a fertility center. Additionally, they noted that there are few similar studies to compare their results against.

"Our findings were contrary to what we initially hypothesized. However, they are consistent with two different interpretations, the first being that low levels of marijuana use could benefit production because of its effect on the endocannabinoid system, which is known to play a role in fertility, but those benefits are lost with higher levels of marijuana consumption," said Feiby Nassan, lead author of the study and a postdoctoral research fellow at Harvard Chan School. "An equally plausible interpretation is that our findings could reflect the fact that men with higher testosterone levels are more likely to engage in risk-seeking behaviors, including smoking marijuana."

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More information: Human Reproduction (2019). DOI: 10.1093/humrep/dez002
Journal information: Human Reproduction

Citation: Marijuana smoking linked with higher sperm concentrations, study finds (2019, February 5) retrieved 20 September 2019 from
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Feb 05, 2019
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Feb 06, 2019
Many of the studies that found damage to the reproductive system were conducted under republican government, meaning that most likely they are false since the republicans lie to impose their agendas. They never had stopped the reefer madness ideology, because they are not able to learn or change their minds based on evidence.

So many years ago when I read that marijuana was bad for reproduction, I started laughing thinking of the rappers filled with children.

Feb 07, 2019
Most Govs were scared of hemp.
EG. In ww2 US army clothes were made from hemp. All rope was made from hemp. Hemp seed oil was used for biodiesel. Hemp seed was a main stay in bird feed. Any hemp that was left (leaves etc) over was used as animal feed.
Hemp roots where left in the ground to fertilise the next crop. In fact the farmer did not even have to seed because enough seed was dropped to produce the next crop. The plant only had to be planted 3" apart for maximum crop density. And you could get 3 or 4 crops a year. Many more benefits.
If you was a Gov that was controlling others economics. Hemp, copra (coconuts) and latex could stop small tropical counties from floundering.
Philippines is a perfect example. With there tropical fruit production, copra and latex they could counter any economic interference. This production was stopped and replaced with plastic production when the US brought them from Spain. Today there a 3rd world country. A source of cheap labour.

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