A review of cannabis use in reproductive health, pregnancy, and fetal outcomes

A recent study was published in American Journal of Obstetrics and Gynecology A review of cannabis use on reproductive health, pregnancy and fetal outcomes.

Study: The effect of cannabis on pregnancy, reproductive health, and offspring outcomes. Image Credit: Yarygin / Shutterstock


Cannabis, a federally illegal drug, is the most widely consumed drug in the United States (US). Its consumption is increasing worldwide in part due to rationing in many regions and growing social acceptance and accessibility. Cannabis use is increasing, particularly among individuals of childbearing age. The high consumption of cannabis during the coronavirus 2019 (COVID-19) pandemic may be due in part to increased stress and anxiety.

The endocannabinoid system mediates the biological effects of cannabis. Expression of the endocannabinoid receptor has been observed in developing fetuses as early as the fifth week of gestation. Cannabinoid receptors have been reported in the male/female reproductive system, sperm and placenta, suggesting that the endocannabinoid system may regulate reproduction. Delta-9-tetrahydrocannabinol (THC), the main psychoactive component of cannabis, has been detected in breast milk and can cross the placenta.

Furthermore, evidence about the safety of cannabis use, particularly in relation to reproductive health and pregnancy, is limited. As such, nearly 70% of females in the United States believe that taking cannabis once or twice a week is harmless. Given the increase in cannabis consumption, it is necessary to study the effects/effect of cannabis on the reproductive health and developmental outcomes of the offspring.

cannabis pharmacology

Hemp is a member of the hemp family and contains more than 80 biologically active chemical compounds, the most common of which are THC and cannabidiol. Cannabinoid receptors (CB1 and CB2) are expressed in the central nervous system and peripheral tissues. Some of the therapeutic properties of cannabis include muscle relaxation, sedation, anti-inflammatory, immunosuppressive, sedative, mood-improving, anti-emetic, and appetite-stimulating, among others. However, cannabis has not been approved for therapeutic use.

Cannabis consumption and legalization

Smoking is the most common way to administer cannabis, followed by foods. Cannabis use disorder (CUD) occurs in about 10% of regular consumers and 50% of chronic users. Treatment options for CUD are limited and include psychosocial intervention, motivational reinforcement therapy, cognitive behavioral therapy or a combination. Several US, African, European, and Australian regions have decriminalized cannabis use.

The reason for the significant increase in cannabis consumption is due to the legalization of recreational cannabis. In the United States, 18 states legalized recreational cannabis in 2021. These legal changes are likely to affect cannabis consumption among teens and children. It has been suggested that puberty and children’s mental health can be affected by cannabis use.

Cannabis use by males and the influence of the father

The effect of chronic cannabis consumption among men is inconsistent, with reports of little or no changes in follicle-stimulating hormone (FSH) levels or poor semen parameters. Animal studies have noted that exposure to THC can lead to adverse effects on spermatogenesis, a decrease in gonadotropins, abnormal sperm morphology, and testicular atrophy.

One recent report showed that exposure to cannabis in rats and humans was associated with altered deoxyribonucleic acid (DNA) methylation. Affected genes have been implicated in cancers and early development, including neurodevelopment.

The effect of cannabis on female reproductive health, pregnancy, lactation, and fetal outcomes

Various studies show that cannabis affects processes associated with female reproductive health, such as ovulation, the secretion of luteinizing hormone (LH) and FSH, and the menstrual cycle. Studies in rats have shown that levels of prolactin, FSH, and LH are suppressed upon acute THC administration. Women who use cannabis during pregnancy often co-administer multiple substances resulting in a synergistic or additive effect.

Furthermore, half of the women who use cannabis continue to use it throughout their pregnancy. There are increasing concerns about adverse fetal/neonatal outcomes as THC can bind to cannabinoid receptors in the placenta or fetal brain. The risk of miscarriage and stillbirth is also higher but is inconsistent in different studies. Some studies have suggested higher odds of admission to the neonatal intensive care unit (NICU), admissions small for gestational age (SGA), placental abruption, and infant mortality.

Impaired cytotrophoblast fusion and biochemical differentiation by THC were observed in vitro. Furthermore, THC inhibits migration of the epithelial layer of amnion, affecting its development during pregnancy and contributing to adverse pregnancy outcomes, including preterm labour. Hyperactivity, impulsivity, abnormal visual and verbal thinking, and inattention have been reported in preschool-aged children born to mothers who used THC during pregnancy.

Nursing mothers are likely to increase their cannabis use within two months of giving birth. This raises concerns about the gradual release of THC from adipose-laden tissues in offspring transmitted through breast milk. Furthermore, chronic cannabis use increased THC concentrations by more than eight times in breast milk compared to plasma. It was observed that newborns exposed to THC within a month of birth had reduced motor development.

concluding remarks

While the use of cannabis is increasing, data on its safety, particularly on reproductive health, is limited. The current literature indicates that its use has significant health effects, and it is of great concern that 70% of females believe that its consumption is safe during pregnancy. Notably, only half of health care providers discourage cannabis consumption in the perinatal period.

Although safety information is limited, it is critical that both individuals and health care providers are aware of the potential negative effects of cannabis, especially before conception, during pregnancy, and during the postpartum period.


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