Research looks at prenatal cannabis use

By Dr. Liji Thomas, MDFeb 19 2020

More and more, pregnant women today are using cannabis, which is mostly for relieving stress and coping with mood changes. However, the risk associated with this for pregnant women who have mental ill-health or trauma is mostly unexplored. A new report published in the journal JAMA Network Open in February 2020 shows that women who used cannabis while pregnant had a higher risk for anxiety and mood disorders.

Cannabis, also called pot, herb, grass, marijuana, and many other nicknames, is a drug obtained from the hemp plant. Botanically, it is from one cultivar of the plant Cannabis sativa and is different from actual hemp,  or industrial hemp,  a strain of the Cannabis sativa species that is grown specifically for the industrial uses of its derived products.

Cannabis is a generic term used to denote the several psychoactive preparations of the plant Cannabis sativa. The major psychoactive consistent in cannabis is ∆-9 tetrahydrocannabinol (THC). Compounds which are structurally similar to THC are referred to as cannabinoids. Image Credit: Lifestyle discover / Shutterstock

The study

In this new study, the researchers looked at over 196,000 pregnancies, of which about 36% were white, 85% were aged 25 years or over, with a mean age of 30 years. The median household income was $71, 000 approximately.

All women were asked about their use of cannabis. A urine test for drugs was also carried out at the first prenatal visit, at about eight weeks of pregnancy on average. Any screening test which returned positive results were then confirmed by more definitive tests.

The health record was used to identify the presence of anxiety, depression, and trauma during pregnancy. Self-reported depression symptoms and violence by the intimate partner were also recorded in all cases at the first visit.

The demographic and mental health characteristics were compared between pregnant women with and without recorded cannabis use. The odds that prenatal cannabis use would be associated with a mental disorder were also calculated.

The results

Among these pregnancies, 6% were positive for cannabis on a drug screen, which comes to almost 12 000 pregnancies. Women who used cannabis were younger on average than those who didn’t and were more likely to be non-whites or Hispanic, but not Asian.

The prevalence of mental disorders was 11% for moderate or severe depression, but only 2% for intimate partner violence. The odds of anxiety disorder were 8% higher in women who used cannabis, 8% higher for anxiety disorder and depressive disorder, and 8% for trauma diagnosis.

Conversely, women with anxiety disorders, depressive disorders, and both had 1.9 times, 2.25 times, and 2.65 times the risk of cannabis use compared to those without these disorders.

Women with moderate to severe depression had twice or more the odds of using cannabis compared to those without this condition.

Women with trauma diagnosis and whose intimate partners had committed violence against them had 1.8 times and 1.9 times the odds of using cannabis compared to those without these conditions.

Limitations

The study was confined to a single healthcare system in Canada, albeit a large one – which means the findings may not be generalizable to all pregnant women. Secondly, all positive cannabis screens may not have reflected use throughout pregnancy, since only one screening is done at eight weeks

Conclusions

The study shows that women with depression, trauma, and anxiety, whether diagnosed or at the trait stage, were more likely to use cannabis than those without these conditions. The conclusion is that pregnant women use this substance to manage mood and stress. There is also a clear relationship between the dose of cannabis and the response. In other words, the greater the chances of cannabis use, the higher the odds that depression and anxiety will also be present, and the more severe the depression is likely to be.

This cannot be interpreted as a cause-effect study, because the reverse could also be true – the use of cannabis might be the trigger or contributor to mental disorders in pregnancy. However, given the complex effects linked with the use of cannabis, the researchers advise: “Pregnant women should be screened for cannabis use, asked about their reasons for use, educated about potential risks, and advised to quit.” Not only so, they reflect, but “early screening for prenatal depression, anxiety, and trauma, and linkage to appropriate interventions might mitigate the risk of prenatal cannabis use.”