Plant-based Medicine and Pregnancy

Plant-based medicine and pregnancy: what do we know?

Plant-based medicine use during pregnancy is a topical issue for both practitioners and patients to address. As prescriptions increase around the globe, the necessity to have a deeper understanding of the impact and risks of cannabinoids on fertility, pregnancy and postnatal health is of supreme importance. 

Plant-based medicine stats for Australian women

Let’s putting aside prescription plant-based products for medical use for a moment and take a look at the stats for illicit substance use. Cannabis is the most frequently used illicit drug in Australia. According to the National Drug Survey conducted in 2016, approximately 10% of women of reproductive age had ingested cannabis in the previous 12 months. 

The University of Adelaide recently published a study of over 5500 women across Australia, New Zealand and the United Kingdom. 5.6% (n=314) of women ingested cannabis before or during pregnancy according to results. Of those 314 individuals, 31% ceased before becoming pregnant, 50% stopped cannabis use before the 15-week mark and 19% continued past 15-weeks gestation.

As the prevalence of legal prescription plant-based medicine increases, the need for quality and relevant research into the impact of cannabinoids on fertility, pregnancy and the child is desperately required if we are to understand how these commonly consumed compounds are impacting a significant number of individuals across our population.


What are the risks of plant-based medicine use and recreational use during pregnancy?

The difficulty in assessing information on the effect of this medicine on pregnancy is that the human research available pertains to pregnant women ingesting recreational cannabis, predominantly through smoking and often with the addition of other confounding risks. Many of the conclusions drawn from such research do not account for the negative impacts associated with tobacco or alcohol separate to plant-based medicine or recreational intake.

Regardless, the known risks associated with recreational cannabis use during pregnancy may include an increased risk of ectopic pregnancy, premature delivery, low birth weight and an increased likelihood of uptake during adolescence.

Health risks associated with tobacco smoking and alcohol intake during pregnancy include a higher chance of negative events such as preterm delivery, placenta problems, low birth weight and birth defects amongst others. Data suggests that of women using recreational cannabis during pregnancy, approximately 65% concurrently smoked tobacco and 85% drank alcohol, with 29% having more than one drink per day.

While there are clear risks and uncertainty in relation to use during pregnancy, this data shows the significant crossover with recreational use to other behaviours that are known to negatively impact the growing child.

This highlights the need to critically evaluate evidence surrounding the direct effect of plant-based compounds on pregnancy, and whether plant-based medicine specifically has any negative impact on the fetus.

The Endocannabinoid System and fertility

The Endocannabinoid System (ECS) is widely recognised in research, yet much of the understanding we have of this unique system has yet to be transferred into clinical practice. In adults, we know that the ECS has great influence over mood, immune responses, digestive function and memory processes.

This system is a part of every individual whether they’ve consumed cannabis in their lifetime or not and is comprised of two main receptors CB1  and CB2. These receptors influence body processes through the action of endocannabinoids, compounds that the body produces innately; and are influenced by exogenous cannabinoids, from botanical or synthetic sources.

Both CB1 and CB2 receptors are found in the female reproductive organs, with local endocannabinoid levels fluctuating with a woman’s cycle. There are heories that dysregulation in the ECS can have far-reaching effects on numerous health outcomes. 

In animal research, the endocannabinoid anandamide is thought to have an impact on successful implantation in its influence over uterine receptivity. Exogenous cannabinoids are thought to interact with the ECS and have been shown to induce muscle relaxation in the fallopian tubes of mice, decreasing the motility of the fertilised egg toward the uterus.

While there is a potential for deviations in endocannabinoid signalling to impact the uterine environment and other processes affecting fertility, translational research interpreting animal investigations of the ECS in the context of human fertility has yet to be conducted and as such, we cannot draw definitive conclusions.

The impact of plant-based chemical compounds on pregnancy and the fetus

There are numerous ways in which we think plant-based medicine may impact pregnancy. Nutritionally folate (or the synthetic form, folic acid) is essential for human health and especially important during pregnancy. Having adequate maternal levels of folate in the lead up to pregnancy is also associated with optimal fetal development as the nutrient plays an integral role in cell differentiation, DNA and RNA synthesis.

Both the main cannabinoids in plant-based medicine have been investigated for their capacity to decrease uptake of folic acid in human cell lines simulating chronic cannabis use. Similar in vitro research points to cannabinoids reducing levels of other important cellular growth factors – however this is early stage research.

Given the rapid cell differentiation and development during pregnancy, the impact that plant-based medicine may have on the growth and development of the fetus would need to be addressed with further studies.

Physiological pathways activated by plant-based medicine compounds that are being investigated for their potential antitumor effects by decreasing cell migration and disrupting the growth of new blood vessels are the same pathways that may pose harmful effects on pregnancy. It is important to note that these actions have yet to be correlated with pregnancy outcomes.


Smoking and the growing child 

Smoking continues to be the primary route of ingestion of cannabis in a recreational setting. It is the process of combustion that poses the greatest concern when smoking. Combustion creates numerous toxic substances such as carbon monoxide and reactive oxygen species, which increases toxic load and requirements for antioxidants. These compounds are known to play a role in the expression of sub-fertility among couples, as well as having a negative effect on the growing child.

Risks of recreational use during pregnancy 

As mentioned there are clear risks in terms of recreational use during pregnancy. A number of studies report an increased incidence of preterm birth and NICU requirements amongst mothers who consumed this substance during pregnancy. However, a 2016 systematic review and meta-analysis came to different conclusions.

When pooling data from 31 studies, the meta-analysis showed recreational cannabis use had negative impacts on birth weight and delivery date. However, when adjusted for the effects of alcohol, tobacco and other illicit substances, the authors found there was no statistically significant evidence of recreational use affecting birth weight, preterm delivery or size for gestational age.

The aforementioned 2020 study conducted by the University of Adelaide contradicted the above meta-analysis. It concluded recreational use was associated with poor fetal outcomes in terms of birth length, weight, gestational age and risk of morbidity, independent of tobacco use. However, for those women that ceased use during early pregnancy, there was less risk of adverse effects. 

In relation to other complications common during pregnancy such as pre-eclampsia, postpartum haemorrhage, gestational diabetes and gestational hypertension, there is a lack of research so please discuss any questions or concerns you may have with your doctor. 


Fetal ECS and THC risk

The ECS in the fetal brain begins to establish from 14 weeks gestation and plays a big role in the development of neuronal connectivity and signalling. In terms of pregnancy, the greatest concern is the impact of THC, the primary intoxicating cannabinoid. This can be found in some prescription formulations of plant-based medicine. It may be only in small amounts, but it is important to discuss the risks properly with your doctor or specialist.

Extrapolations from animal studies indicate THC readily crosses the placental barrier and has relatively slow clearance. How this primary and intoxicating cannabinoid might interact with the fetal ECS and impact development is largely unknown, what we do know is optimal fetal developmental processes exist within a tightly regulated range. 

While fetal and maternal endocannabinoids are likely to play a significant role in the healthy development of the fetus, exogenous cannabinoid exposure at critical points of neurodevelopment could have a deleterious effect and must be further investigated. 


The ethics of plant-based medicine research on pregnant women

While in general the application of plant-based medicine in a supervised and clinically appropriate manner is vastly different to the effects illicit use has on the body, in the case of pregnancy that point proves relatively moot. Given the inherent risk and evidence tending towards recreational use having a negative effect on pregnancy, there is little foundation to support investigating the application of pharmaceutical-grade plant-based medicine during pregnancy. 

Simply put, it may be considered unethical, even if researching the impact of plant-based medicine is important. Therefore our understanding is limited to extrapolations from animal studies and observational research of pregnant women using illicit, or in some international cases, legally accessed recreational products.


Can plant-based medicine help with nausea during pregnancy?

Given the association with treating symptoms of nausea with plant-based medicine, it is understandable there is interest in how it might be able to help alleviate nausea during pregnancy, particularly for those women struggling with hyperemesis gravidarum. 

The clinical outcomes observed in utilising plant-based medicine for nausea relief has generally been limited to chemotherapy-related presentations. Whether synthetic or botanically derived, it is the THC component that is largely responsible for the anti-nausea action of plant-based medicine in some patients. Irrelevant of other concerns surrounding intake during pregnancy, the extent of negative effects of this compound on the growing fetus and subsequent development of the child, is not well enough understood and is therefore avoided in a clinical setting.


Taking plant-based medicine during pregnancy

Few international physicians believe that well monitored application of the non-intoxicating cannabinoid CBD during pregnancy may be beneficial. Anecdotally, some women have reported its intake during pregnancy to help with symptoms such as nausea, vomiting, sleeplessness and pain. Despite symptoms such as these being sometimes treated as an adjunct therapy in other settings, medical professionals err on the side of caution in the instance of pregnancy.


The wrap-up on plant-based medicine and pregnancy

Conflicting evidence and lack of trials outside an observational setting makes it difficult to assess the direct impact of specific cannabinoids on pregnancy and fetal outcomes. In general, any substance that impacts the delicate balance of maternal physiological processes has the capacity to impact the baby, and as such, clinicians will caution against its use. As always, the best path forward is to seek the advice of a medical professional if you are considering plant-based medicine treatment or consuming recreationally both directly prior to or during pregnancy.

DISCLAIMER: Cannabinoid products are unapproved therapeutic goods, which means they have not been assessed by the TGA for safety, quality or effectiveness. However, where clinically appropriate, there are pathways for doctors to access cannabinoid products for their patients. Note that plant-based medicine does not have therapeutic effects for all patients and may not be medically appropriate for you or your condition. It is always important to check with your doctor before considering plant-based medicine as a treatment option for you, especially if you are already taking other medications. as some patients may experience side effects. None of the content here is an encouragement or inducement to try or use plant-based medicine, and is for educational and informational purposes only

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