Cannabis & Fertility

Taking illegal drugs is not something we often want to disclose to our healthcare professionals, so perhaps you’re a little in the dark about the effects of cannabis use on fertility. Here we are to shed some light.

For the Men:
For many years, data and research about cannabis use and fertility has been minimal. And still, there is quite limited evidence, however a meta-analysis (a review of all available other studies on the subject) in 2019 found that cannabis use may have a significant detrimental effect. This review found that in general, sperm count, concentration and motility are affected, which significantly reduces their fertilising capacity. Studies in animals have also shown reduced libido with cannabis use, however this has not been found conclusively in humans yet. If this is the case however, it shows cannabis could reduce likelihood of conception two-fold: not only are sperm in each ejaculate less in number and less efficient, but also the frequency of ejaculates are diminished due to low sex drive.

For the Women:
Again, unfortunately research is limited, but data does  show  that  ovulation was delayed or inhibited in some populations of marijuana users, however the study samples were not large enough to give conclusive evidence. There has been some research finding that regular marijuana use may cause disruption to some reproductive hormones, such as reducing the peak in lutenising hormone (which would explain the delayed or inhibited ovulation), however it seems that this effect may be dependant on when in the menstrual cycle marijuana is taken.

In Pregnancy:
Research has found that women who regularly smoke cannabis prior to conception experience a higher rate of pregnancy-related nausea, even if they stop cannabis use while pregnant.This could be seen as controversial as there have been plenty  of women who report that cannabis reduces ‘morning sickness’ in pregnancy, and even use medical cannabis products to this effect. Cannabis Hyperemesis Syndrome, which is characterised by abdominal pain, nausea and vomiting and common among long term cannabis smokers, is commonly found to be resistant to the effects of anti-sickness medication. This can be problematic if pregnancy sickness is combined with cannabis hyperemesis syndrome, as it leaves the mother at risk of becoming malnourished and dehydrated.

Continued use of cannabis during pregnancy has been found to have adverse effects on the developing foetus. These include lower average birth weight, some instances of withdrawal symptoms after birth, and even implications on mental health and increased mood instability in the growing child.

Postpartum:
Breast milk is the best source of nourishment for your baby, as your body has the incredible capacity to tailor it to exactly what your baby needs. However, as the active part of cannabis, THC, is a fat-soluble molecule, it can pass freely into breast milk and therefore affect baby. However, due to mothers not reporting all cannabis use, and that carrying out studies which  require mothers to take cannabis would be completely unethical, there is very limited research into the effect of cannabis use in breastfeeding. Therefore, even though all studies mentioned here point towards detrimental effects of cannabis, there is not enough evidence to say conclusively that cannabis use is unsafe.

The rational conclusion?

Marijuana is the most commonly used illecal drug during pregnancy, and despite  often being thought of as a ‘herb’ and a completely ‘natural’ drug, the current evidence base points towards it being detrimental for fertility, pregnancy experience, and post-natal outcomes. Therefore, to facilitate the best chances of conception and healthy pregnancy, it would be sensible to cut out cannabis use, especially during this important time.

Resources:
PMID: 32060189
DOI: 10.3389/frph.2022.820451
DOI: 10.1097/JU.0000000000000248
DOI: 10.1089/jwh.2007.0354