Introduction

Cannabidiol (CBD) has been going through a PR makeover over the last few decades, especially in medical use. Cannabis, the plant it is sourced from, was once only known as the “devil’s lettuce” and feared for its potentially addictive properties. However, in light of recent research, we now know that CBD has the potential to be a valuable treatment for a variety of illnesses, including epilepsy. 

There is a common misconception that cannabis and CBD are the same thing, but this is incorrect. Cannabis is a term used to describe all plants that produce cannabidiol (CBD) and tetrahydrocannabinol (THC). Marijuana is a type of cannabis plant that contains much more THC than CBD. In other words, all marijuana is cannabis, but not all cannabis is marijuana. When people talk about the psychoactive properties of marijuana (think the ‘munchies’ or ‘getting high’), the culprit is THC. However, CBD does not cause the psychoactive effects usually associated with cannabis. In fact, with many countries changing laws regarding cannabis use, there is growing evidence that CBD may be able to help treat a variety of conditions, including inflammation, vomiting, and epilepsy.¹  

Epilepsy is a brain condition characterised by recurring unprovoked seizures.² The following can be categorised as epilepsy:

• At least two unprovoked seizures occurring more than 24 hours apart
• One unprovoked seizure and a high risk of further seizures occurring after two unprovoked seizures, over the next 10 years
• Diagnosis of an epilepsy syndrome³

It can affect people of all ages worldwide, with 80% of active cases in middle to low-income countries.^{.4, 5} Having an electroencephalography (EEG)  is considered the best way to check brain activity to evaluate the severity of the condition.

People living with epilepsy may face social, economic, and psychological difficulties depending on the severity of the condition.⁴ These difficulties can be further compounded for pregnant women living with epilepsy. However, very few studies are available that examine safety and efficacy in pregnant women. Most anti-seizure medications are safe for use during pregnancy. However, studies have shown epilepsy and the use of anti-seizure medication during pregnancy are associated with decreased foetal growth and complications such as pre-term birth and spontaneous abortion.⁵ There is a need for alternative treatment routes for pregnant women living with epilepsy. 

How does CBD work in treating epilepsy?

It is still unclear how CBD helps to control epileptic seizures. However, research suggests that CBD may help by regulating the levels of calcium ions and adenosine signalling in the brain.

CBD showed promise in one study where a 36.5% reduction in motor seizures was reported in patients. In the same study, five patients were free of motor seizures altogether. There is also increasing evidence that CBD is effective in children. One study that involved 108 children using CBD oil over 6 months reported that 29% of participants saw a 50% reduction in seizures, with a further 10% of participants reporting being seizure-free.¹ 

CBD use during pregnancy: what do we know so far?

Currently, there is no official guideline on the safe level of CBD intake for pregnant women. There is very little data on CBD use in pregnant women. The small amount available has been collected mainly by self-reporting. As with any self-reporting study, it is difficult to estimate the accuracy of the data, as there could be a higher amount of usage, but participants may feel uncomfortable sharing information. 

One study found pregnant women who use CBD during their pregnancy are more likely to do so during the first trimester. Vomiting and nausea from morning sickness were reported as one of the main reasons for CBD use.⁶ We already know that there is evidence that CBD can be used to ease vomiting, so this lines up with current research.¹  

The most obvious reason for the lack of clinical trials investigating CBD during pregnancy is the unknown risk to the developing foetus. CBD can dissolve in fats and oils. Because of this property, it is easy to cross through body tissues such as the placenta. This tends to happen with other anti-seizure medications. 

The side effects of CBD on foetuses are currently unknown, but a proposed risk could be low birth weight or possible neurological effects, which is yet to be confirmed.^6,7 However, the placenta functions as a “filter” accumulating potentially harmful substances in its membrane to reduce direct exposure to the foetus. In other words, the placenta could be a defence mechanism to protect the foetus from CBD exposure. One study examined the placentas of mothers who had elective caesareans and used CBD during their pregnancies. A low mother-to-foetus ratio was found. It is still unclear how this occurs, but research suggests that the placenta accumulates CBD and slowly diffuses it, thus resulting in low levels of CBD reaching the fetus.⁷

Current guidelines for epilepsy management during pregnancy

Generally, 90% of pregnant women living with epilepsy go on to deliver healthy babies with no major medical incidents during their pregnancy. Still, there are unique challenges that they must take into consideration:

• Seizures and resulting blunt force trauma. Seizures can also leave the foetus at risk of suffocation
• High blood pressure in the fetus
• Pre-eclampsia⁸

Epilepsy is the most common neurological condition in pregnant women, affecting 0.3% - 0.8% of all pregnancies. While it is generally safe for pregnant women with epilepsy to continue treatment, careful consideration is needed to determine what type of treatment is safe to use. 

Anti-seizure medication like valproate and phenobarbital is not recommended for pregnant women as it runs the risk of causing cognitive and behavioural impairment in babies. Alternative options can include lamotrigine or levetiracetam as they are considered low risk of causing foetal harm.⁸ 

Venn diagram displaying anti-seizure medication and their risk of causing neurodevelopmental issues in babies. Made by Victoria Danquah based on Figure 2-3 from Li and Meador (2022)⁸

Folic acid is an essential supplement for pregnant women in general, but especially for women living with epilepsy. A dose greater than 400 mcg/d would usually be recommended, especially during the first 12 weeks of pregnancy.⁸

Close anti-seizure medication monitoring would be implemented to monitor the development of the fetus, with adjustments needed as required. The key goal would be to establish seizure control as soon as possible. Research suggests that it is safe for new mothers who have taken anti-seizure medication during pregnancy to breastfeed their babies.⁸

Losing sleep, anxiety, and postnatal depression are associated with an increase in seizures. For this reason, it is vital for pregnant women in general, especially those living with epilepsy, to have an active and nurturing support system alongside healthy coping mechanisms to ensure new mothers have enough rest and adequate sleep. This will help reduce the number of seizures occurring and improve both mental and physical health.⁸

Summary

CBD may be a promising alternative for pregnant women who want something to help alleviate morning sickness symptoms and reduce the frequency of their seizures, but are concerned about the potential effects certain anti-seizure medications, such as valproate and phenobarbital, can have on their babies. CBD has the potential to offer therapeutic benefits for a wide range of diseases. 

Studies indicate that CBD may have a low risk of adverse effects on the developing foetus, but more research is needed to explore this. There is no official guideline for CBD use in pregnant women. While clinical trials are reluctant to involve pregnant women for obvious reasons, more data are needed to determine CBD safety baseline levels suitable for pregnant women. 

Thankfully, the vast majority of pregnant women living with epilepsy go on to have normal deliveries and healthy babies. The current guidelines recommend the following to ensure a healthy pregnancy:

• Folic acid supplements
• Getting enough sleep and post-natal support
• Close monitoring of anti-seizure medication 
• Switching to treatment options that pose a lower risk to the developing fetus. For example, switching from valproate to lamotrigine or levetiracetam