The use of marijuana, also known as Cannabis, has a direct and negative impact on male and female fertility in case of heavy smoking. In this article, we offer an overview of cannabis and its consequences in fertility, especially in those already having poor health.

More than 17 million cannabis users in the United States

In the United States of America, it is estimated that more than 17 million people are marijuana users, with 4.6 million who admit to using them almost daily. Up to 22% of men who intend to have children claim to have consumed it in the last 12 months. Unlike tobacco, cannabis has a very slow elimination and its deleterious effects are more important. The half-life of its psychoactive ingredient, tetrahydrocannabinol (THC), metabolized by the liver, ranges from 20 to 36 hours in occasional users to 4 to 5 days in heavy users. It may require 30 days for its complete elimination of the body.

Marijuana affects the reproductive system

The current debate on the legalization of cannabis in Canada has recently been a good opportunity for psychiatrists to publicly intervene and to recall some of its negative health effects, including adolescent brain development, deterioration of cognitive functions and the potential outbreak of latent psychotic diseases, such as schizophrenia. The effects of cannabis, 300 to 400% more powerful than 30 years ago, are not limited to the brain but interact with several organs of the body and can, therefore, influence their functioning. This is particularly the case of the reproductive system.

Infertility affects both men and women

While couples' infertility is not very widespread (4-5%), it is still a very difficult episode. And the more frequent use of medically assisted procreation may suggest that this phenomenon is increasing. Almost a quarter of couples would consult a doctor at some point in their lives for fertility problems.

For many years, fertility problems were considered to be predominantly female. For cultural and social reasons, male infertility has long been ignored. Today, the taboo is lifted and it is considered that more than a third of the cases would be related to the man.

Infertility is on the rise due to cannabis

Some infertile couples, who regularly consume marijuana, sometimes feel judged or even struck when, at the first medical consultation, the doctor asks them to stop using the drug and to seek help in the presence of an addiction. However, this claim is scientifically based.

Nowadays, about 17% of couples are unable to conceive. Infertility is on the rise since its prevalence was only 5% in the 1980s. In the face of this increase in infertility, particular attention is increasingly paid to bad habits and regular exposure to environmental toxins that can be prevented and harmful to human reproduction especially marijuana.

Its impact on the male reproductive system

Beyond cultural changes, several studies have suggested that male fertility is generally on the decline. Industrial pollution, chemical effluents, smoking ... The suspects are numerous, but scientists lack real evidence. But one thing is sure; the consumption of cannabis has consequences on the quality of the seminal fluid. In 2003, the sperm study of 22 men who smoked cannabis 4 times a week for 5 years showed fewer spermatozoa and abnormal behavior: they moved too fast and too early. Much less likely to reach the egg and thus fertilize it. The consumption of cannabis could thus render infertile men who are already poorly fertile.

It affects the spermatozoa

A 2006 research that studied in vitro the effects of THC on the function of spermatozoa of 78 men with an infertility assessment showed a deleterious effect on the number and function of spermatozoa. It is worth noting that cannabis use in a woman may also result in these effects on the spermatozoa in the genital tract: a high rate of THC is found in the female genital tract. It is not yet explained why cannabis has such an effect but hypotheses have been put forward.

THC would act on cannabinoid receptors present on the surface of spermatozoa and alter the endocannabinoid system in the testes. Marijuana use also has an effect on sex hormones: studies in rats and monkeys have shown a reduction in sex hormones: Luteinizing hormone (LH), testosterone and FSH (Follicle-Stimulating Hormone), but LH and HFS are two hormones that are of major reproductive importance in humans (they control spermatogenesis). However, other studies have shown an onset of tolerance, which means that cannabis users can have normal levels of hormones.

In addition, cannabis smokers are also very often tobacco users (joints), but many studies have shown that tobacco smokers have poor sperm (less sperm, less mobile, chromosomal sperm abnormalities) and consequently poor fertility. It is therefore known that the combination of tobacco and cannabis has deleterious effects on reproduction.

Moreover, cannabis smokers are also very often tobacco users (joints), but many studies have shown that tobacco smokers have poor sperm (less sperm, less mobile, chromosomal sperm abnormalities) and consequently poor fertility. It is therefore known that the combination of tobacco and cannabis has deleterious effects on reproduction.

Heavy cannabis smokers are warned!

Several original studies were presented at the annual congress of the American Society of Reproductive Medicine. The most surprising results are the adverse effects of marijuana use and overweight. A previous in vitro study suggested that the active substance of cannabis (tetrahydrocannabinol or THC) could inhibit fertilization of the ovum by the spermatozoa and limit its mobility.

In the presence of THC, these fertilizing adventurers could only maintain a sustained rhythm for 6 hours, whereas it took 24 hours or more to reach the egg. The same team wanted to know if these laboratory observations could be found on users of marijuana. They have recruited 22 regular smokers (more than 4 times a week) since on average 5 years. Analysis of their sperm revealed that:

  • The volume and total number of spermatozoa were significantly reduced in smokers;
  • The morphology and mobility of the spermatozoa were unchanged;
  • The velocity of the spermatozoa was very abnormally, very early. Required when approaching the egg, this hyperactivity reduces fertility abilities when premature. The spermatozoids burning all their energy from the start...

According to the authors, all these factors jeopardize the fertility potential of cannabis smokers but also smokers with a high rate of THC in their genital tract. Scientists do not specify the time of abstinence necessary for reproductive capacity to return to normal.

An adverse effect on female reproductive function

Regular consumption of cannabis in women results in disruption of the cycle and the quality of ovulation. This is due not only to THC but also to other components of cannabis. For example, it appears that phytoestrogens in cannabis smoke interfere with estrogen receptors. THC causes disturbance of sex hormones.

Experiments have shown that acute administration of THC modifies the secretion of luteinizing hormone (LH), but varies according to the period of the menstrual cycle. Thus, a high exposure to cannabis during the progestational phase reduces the plasma level of luteinizing hormones by 30% within one hour of consumption, whereas in the periovulatory period this exposure leads to an increase in LH secretion.

The luteal phase is less well developed

The luteal, a stage in a menstrual cycle, occurs after ovulation (when the ovaries release an egg) and before the period starts. The consequence of consuming marijuana is that the luteal body is less well developed. Female monkeys have been shown to inhibit LH and FSH hormones. A study of 26 women who smoked cannabis at least 4 times a week showed that THC disrupted the menstrual cycle, with a shorter cycle and a shorter luteal period. One study showed an increased risk of functional ovarian cysts in cannabis smokers, but these can be related to infertility problems. Cannabis also has an adverse effect on in vitro fertilization.

Cannabis smokers also consume tobacco, which also has repercussions on female fertility. The consumption of tobacco leads to a decrease in the ovarian reserve, a decrease in the quality of oocyte (a cell in an ovary which may undergo meiotic division to form an ovum), short and irregular cycles, and dysmenorrhea. But unlike cannabis, which is very slow to eliminate, the effects are reversible if the consumption is stopped. The consumption of joints is thus doubly harmful to female fertility.

More difficult to conceive when consuming cannabis

Studies in animals have shown that the use of cannabis at the time of conception has increased the risk of miscarriages and ectopic pregnancies. It appears that THC prevents the transport and nesting of embryos in the uterus. A natural molecule, anandamide is present in early pregnancy. It is necessary for the implantation and development of the embryo. If this molecule is present in too large or too small quantities, problems can arise in the transport of the embryo in the uterus, its implantation in the uterus and its development. Studies on mice treated with Delta-9-THC showed a 40% increase in the rate of early miscarriages and an absence of embryos in the uterus in 35% of cases. THC results in a higher than normal concentration of anandamide.

Again, it is necessary to talk about the effects of tobacco on conception, as cannabis users often consume it with tobacco. The Augood study (meta-analysis of 12 studies) showed a conception delay of more than one year which is dose-dependent with duration of exposure to tobacco and the rate of failure of ICSI was 3 times higher among smokers.

The current knowledge, although to be confirmed for some, advises couples who want to have a child to stop tobacco and cannabis, and this is even more valid for those who are being followed for infertility and who have recourse to medically assisted procreation.

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