Past research has indicated that cannabis use may disrupt the menstrual cycle, suppress oogenesis (production of eggs in the ovaries) and impair embryo implantation and development. Chronic use of cannabis has also been repeatedly associated with lower birth weight (as much as a 50% increased risk), decreased birth weight and early (spontaneous) termination of pregnancy.
The 2002 study provides strong evidence that the presence of the anandamide in the seminal fluid, and its ability to bind to the CB1-receptors of the spermatozoa, are key to the “capacitation” of sperm cells on their way to the ejaculatory ducts. It has to be present in the appropriate concentrations, though. If the level of anandamide is too high, it can instead have a dramatic inhibitory effect on the sperm cells’ ability to fertilize oocytes.
As is so often the case with cannabinoid science, dosage is everything—and it may prove to be the case that very small doses of THC could benefit males who have reproductive issues that can be tied to low levels of anandamide.
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And an even earlier study (Kolodny et al, 1974) into testosterone levels in “chronic” cannabis users found that 6 of 17 subjects had oligospermia (low sperm count), and that average testosterone levels in the cannabis-using group were just over half that of the control group. The effect of cannabis on testosterone levels was observed to be dose-dependent.
Other studies seen as providing evidence that cannabis use can cause foetal abnormalities are animal studies (Geber & Schramm 1969, Phillipset al, 1971) in which rabbits, hamsters, rats and mice were injected with vast doses of crude cannabis extract (as much as 666mg/kg in one instance!). Such massive doses of cannabis would be practically impossible for a human to consume through conventional means, and are essentially useless as a point of comparison.
Some studies on the effect of cannabis use on male fertility have indicated that regular use may reduce spermatogenesis (the production of sperm in the testes) and testosterone levels.
Use of cannabis may affect human fertility, depending on gender, general health, socioeconomic status and several other factors. Here, we look at existing research on cannabis and human fertility, in order to provide readers with an accurate, up-to-date summary of the current state of scientific knowledge.
Although the link between marijuana and fertility is not straightforward—plenty of marijuana smokers get pregnant and get their partners pregnant—some research has demonstrated that marijuana use can negatively impact you, your partner, or the fertility of both of you.
Research suggests that marijuana can negatively affect female fertility in the following ways:
Quitting marijuana can be harder than many long-term marijuana users expect, so you and your partner would be wise to quit as soon as possible, while you still have time to get help before getting pregnant. If either or both parents still use marijuana when the baby arrives, you are increasing the risk that your child may use drugs in the future, and parental drug use is implicated in many difficulties for children and families.
Obviously, if you are both smoking marijuana, you risk increasing the chances of infertility as a couple.
Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital.
According to the Eunice Kennedy Shriver National Institute of Child Health and Human Development, approximately 9 percent of men in the United States have faced infertility.
The researchers’ findings, which they report in a study paper that features in the journal Human Reproduction, ran counter to the hypothesis that they established at the beginning of the study.
Another finding reported in the study indicates that marijuana smokers who used the substance more frequently also tended to have higher blood testosterone levels.
More specifically, marijuana users had an average sperm concentration of 62.7 million sperm per milliliter of ejaculate, whereas their peers who had never smoked marijuana had 45.4 million sperm per milliliter of ejaculate.
For this reason, researchers have been looking at how different modifiable factors, such as lifestyle choices, might affect male fertility.