Smoking THC in your teens slashes your egg count in HALF, study suggests 

Teenage girls who smoke marijuana may be permanently harming their fertility, researchers warn.

A study led by the University of California, Irvine (UCI), found adolescent female mice exposed to tetrahydrocannabinol (THC), the psychoactive chemical in the drug, had 50 percent fewer healthy ovarian follicles than the control group by the time they were adults.

Researchers believe the body’s endocannabinoid system — which is stimulated when marijuana is used — damages follicles or causes them to activate too quickly, depleting them.

With marijuana use now commonplace among teens across America, researchers fear many young women are unknowingly damaging their likelihood of having a child in the future.

While the latest study was on mice, separate research has shown that pregnant women who use cannabis are at a greater risk of birth defects, miscarriages and stillbirths. 

Researchers found that mice who were regularly exposed to THC over two weeks had 50 percent fewer healthy ovarian follicles, including primordial follicles that represent the number of eggs a woman will have for the remainder of her life

Marijuana is legal for recreational use in 21 US states and Washington DC (orange). It is available for medicinal use in 17 states (green)

‘Given that more and more teenagers and young adults are using cannabis, especially with easier access to the substance, this study’s findings are especially important,’ Dr Ulrike Luderer, lead author of the study and professor of environmental health at UCI, said.

‘It is imperative to widely broadcast the consequences of early-life exposure to cannabis on reproductive health in adulthood.’ 

An estimated 3.3million US teens between ages 12 and 17 use cannabis, experts warn.

Use of THC, the chemical within the drug that gives someone the ‘high’ feeling, has been legalized recreationally in 21 US states and the District of Columbia.

Nearly all of these states made the change in the time since the Covid pandemic, seeing the boosted tax revenue from marijuana sales as an opportunity to fill state coffers.

While it was already frequently used as a street drug, the widespread legalization of it has spiked marijuana use among young Americans.

A study published at the end of last year by Oregon Health & Science University found that cannabis use among American teens increased 245 percent from 2000 to 2020. 

There is not much research on the potential harms of widespread cannabis adoption. 

Early signs point to many long-term negative effects from using the drug, though, including heart problems, cognitive issues and lower IQ.

In November, researchers found that marijuana use increased a person’s risk of developing deadly heart condition atrial fibrillation by more than 30 percent.

Now, the UCI study finds that young women in particular may be putting themselves at risk by using the drug.

The researchers, who published their findings in the journal Toxicological Sciences, injected mice that were around 30 days old with THC daily for two weeks.

These mice would be considered adolescents, as the species reaches adulthood at around three months old.

When the mice reached 70 days old, researchers checked how many primordial follicle ovaries they had.

These are ovaries in the earliest stages. They will eventually develop into eggs that a woman will ovulate.

Like mice, female humans are born with the ovaries they have throughout her life. A lower ovary count significantly reduces her chances of getting pregnant in the future.

They found that mice who had been exposed to the THC had half as many follicles as other mice of the same age.

This was the case at all stages of ovary development, meaning the mice exposed to the drug were overall less fertile than their peers.

‘Our findings provide unexpected new insights into the long-term impact of THC on reproductive function and aging,’ Dr Daniele Piomelli, co-author of the study and professor of anatomy and neurobiology at UCI said.

‘Our hope is that our findings will motivate teenage girls to make better, more informed decisions about whether or not to ingest cannabis products.’ 

This is not the first study that has linked THC use to worse fertility.

A 2018 study found that men who smoked cannabis had lower sperm counts than their peers.