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Avoiding Cannabis 74 Days Before Conceiving Lessens Impact On Sperm Quality, Says Study


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer

man smoking cannabis

According to a new study, there is one thing a future father might want to consider abstaining from: cannabis. Image Credit: Elnur/Shutterstock

Alcohol, tobacco, bougie cheese – there are many things a person has to give up if they’re trying to get pregnant. However, we don’t often hear about the other half of the situation having to make any sacrifices for their future fetus’s health – no switching to decaf or swearing off cookie dough for them.

According to a new study, there is one thing a future father might want to consider abstaining from: cannabis. Published this week in the journal Environmental Epigenetics, the research suggests that giving up the devil’s lettuce for a few months before conception can be crucial for diminishing the effects of the drug on sperm.


“Stopping cannabis use for as long as possible – at least for a 74-day period before trying to conceive – would be a good idea,” said lead author Susan Murphy, associate professor in the Department of Obstetrics & Gynecology at Duke University School of Medicine. “If someone is really serious about that, I would say to stop cannabis use for as long as possible prior to conception – meaning multiple spermatogenic cycles.”

Scientists already knew that cannabis and THC exposure can have troubling effects on fetal development – particularly brain development. Higher levels of intellectual disability and learning disorders in children had previously been linked to the use of cannabis while pregnant, and recent research has started to show that paternal cannabis use also seems to have an impact. Exactly how and why these effects occur is more of a mystery, but one study last year did provide some insight: cannabis use is associated with widespread changes in how certain genes are expressed in sperm cells.

What researchers didn’t know, though, was how permanent those changes were. If a person were to quit using the drug for the same length of time it took to replace all the sperm cells in their body, would they be able to avoid passing the effects onto their offspring?

“The duration of human spermatogenesis [the development of new sperm cells from stem cells] is ∼74 days,” explains the study. “It is reasonable to hypothesize that […] effects are not permanent, with affected sperm removed over time by ejaculation or reabsorption."


"The objective here was to determine if men who stop cannabis use for 11 consecutive weeks resolve cannabis-associated epigenetic changes in their sperm.”

The good news is that after 77 days of abstinence, the levels of altered genetic information in sperm samples were far lower than when cannabis was being used. However, they hadn’t disappeared completely, and the bad news is that the researchers aren’t totally sure what impacts the remaining effects might have.

“We don't know yet whether the alterations that we're seeing are at genes that have a stable characteristic,” said Murphy, “or if they are in genes that get reprogrammed and really are going to be of no consequence to the child.”

The authors of the paper write that "Autism spectrum disorders (ASDs) have been put forth, with epidemiologic support, as the most common form of cannabis-associated teratology." One study even indicated that when cannabis use is legalized, autism diagnoses increase. While she takes no stance on legalization, Murphy believes the new findings are important to enable parents-to-be to better understand how their choices might affect their future progeny.


“Is [not using cannabis] going to fix everything? Probably not,” she said. “We know there are other epigenetic changes that emerged in the 'after' sample that we don't understand yet – and some of those changes are troubling, like an enrichment of other genes related to autism. But it does appear that the things that were the most severely affected in the 'before' sample seem to be mitigated by the abstinence period in the 'after' samples.”



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