Cannabis use during pregnancy linked to low birth weight: Study
- The study tracked 9,000 pregnant people who had a range of cannabis use
- The study found sustained use throughout a pregnancy increases risks
- Low birth weight was the outcome most associated with cannabis use
FILE – Marijuana plants grow at a Minnesota Medical Solutions greenhouse on May 5, 2015, in Otsego, Minn. Senators in Minnesota passed a bill Saturday, May 20, 2023, that would legalize recreational marijuana for people over the age of 21, making it the 23rd state to legalize adult-use cannabis. The measure has already been approved by the House and now goes to Democratic Gov. Tim Walz, who has pledged to sign it into law. (Glen Stubbe/Star Tribune via AP, File)
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(NewsNation) — Cannabis use has been linked with a greater risk of unhealthy pregnancy outcomes, especially low birth weight, a new study found.
The prevalence of cannabis use has surged in the past decade as more states legalize it for medical and recreational use. Some pregnant people use cannabis to help manage their symptoms, like nausea and pain.
The study analyzed more than 9,000 pregnant people between 2010 and 2013 to determine whether they had used cannabis at any point during pregnancy, at what point in the pregnancy it was used and how much was used, according to the report published Tuesday in the Journal of the American Medical Association.
The team measured THC levels at three different points in the pregnancy and used it to calculate the total cannabis exposure throughout the pregnancy, finding a higher use associated with a higher risk to the pregnancy.
“We found that cannabis use during pregnancy was associated with a risk of poor pregnancy outcomes,” said the study’s lead author, Dr. Torri Metz, a high-risk obstetrician and an associate professor at University of Utah Health. “And the risk increased with increasing use during pregnancy. This shows that it’s best not to use cannabis during pregnancy.”
The researchers found pregnant people who used cannabis had “adverse pregnancy outcomes” at a rate of 25.9%, while those who did not use cannabis had adverse outcomes 17.4% of the time.
Of all the adverse outcomes observed in the study, low birth weight was the one most associated with cannabis use.
Low birth weight was defined as less than 5 lbs., 8 ounces at birth. This can lead to a range of health complications and long-term risks, including an increased likelihood of chronic conditions later in life.
The other adverse outcomes associated with cannabis use were preterm births, stillbirths and hypertensive pregnancy disorders, the study found.
The study also determined the highest risks were associated with ongoing use throughout the pregnancy. This suggests patients who stop using cannabis early on, especially in the first trimester, can significantly reduce the risk of problems.
“Looking at any adverse outcome, we saw that people who had stopped use within the first trimester didn’t actually have a statistically significant increased risk (vs.) those who had continued use,” Metz said.
The research also accounted for tobacco use, which is well-known to be dangerous during pregnancy.
“One of the questions in previous studies has been, ‘How much of this is related to nicotine?’ because there’s a lot of co-use of cigarettes and cannabis,” said Smita Das, a psychiatrist at Stanford University who specializes in addiction and who was not part of the study. “The authors are able to adjust for cigarette smoking status,” she said, adding that “this study is an excellent quantitative assessment of cannabis use.”
