S The study is published in the scientific journal journal Addiction and lead author is Ban Al-Sahab, associate professor, public health scientist and epidemiologist in the Department of Family Medicine at Michigan State University. [1]
Her research group initially states that the self-reported cannabis use among women in the United States who are expecting a child has increased from 2.4 percent to 7 percent between 2002 and 2017. This is in line with an increasing number of people believing that the drug is harmless.
In 2005, 25.8 percent of pregnant women who had used cannabis in the last month believed that the use was not harmful. Ten years later, 65.4 percent of the same group believed that cannabis was harmless.[2] This despite the fact that the drug is constantly getting significantly stronger. Among non-cannabis smoking pregnant women, the perception of risks was significantly greater.
Stronger evidence of harm
The harmful effects of cannabis on the fetus are becoming increasingly well documented.
It is known that THC, the intoxicating substance, passes into the placenta, which can cause premature birth and lower birth weight. Other increased risks in the children may be developing ADHD, autism and other neuropsychiatric conditions.
The mother also runs a somewhat greater risk of side effects such as high blood pressure and preeclampsia (preeclampsia with cramps).[3]
More and more people are using cannabis
Al-Sahab’s study is based on data from 1,105 first-time pregnant women from 20 different clinics in Michigan. For virtually all, there was information on the women’s cannabis habits, both through urine samples and self-report. Sampling is especially important because previous surveys of pregnant women show that they often underreport their own use.
The current study refers to previous research: in California, 2.5 percent of pregnant women between 2009 and 2017 reported using cannabis. However, when compared with urine samples, there were twice as many. An even greater difference was noted in Colorado in 2016. There, six percent of newly delivered women said they had used cannabis in the past month, while 22.4 percent tested positive for cannabis in the umbilical cord.
In the Al-Sahab study, 16.8 percent of pregnant women, i.e. one in six, had recently used cannabis.
The practice was twice as common among single women compared to those living in couples. It was also twice as common among the depressed and almost four times more common among those without a post-secondary education to use the drug.
Relief of stress and anxiety
According to the researchers, there are several contributing reasons why pregnant women use cannabis to an increasingly greater extent. Partly because as many as one in five of them do not believe that the practice is harmful, even if you smoke every week, and partly because the drug has become cheaper and very easy to get hold of.
In Michigan, the medical use of marijuana was legalized in 2008. In 2018, the drug became legal for recreational use by all adults, and prices have been reduced. Another reason for the practice among pregnant women is perceived relief from stress and anxiety.
References:
[1] Al-Sahab et al (2025). Prevalence and characteristics of prenatal cannabis use in Michigan, USA: A statewide population‐based pregnancy cohort. Addiction, 121(1), 126–137. – Al‐Sahab – 2026 – Wiley Online Library
[2] Jarlenski et al (2017). Trends in perception of risk of regular marijuana use among US pregnant and nonpregnant reproductive-aged women. American Journal of Obstetrics & Gynecology. Research Letter. Volume 217, Issue 6
[3] Young-Wolff et al (2024). Prenatal Cannabis Use and Maternal Pregnancy Outcomes, JAMA Internal Medicine Vol. 184, No. 9. | Substance Use and Addiction Medicine | JAMA Internal Medicine