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Pregnant Women are Using Marijuana for Morning Sickness. Study on Rats Suggests This Could Affect Baby’s Brain

April 9, 2019 – By Kashmira Gander, Newsweek

Using cannabis while pregnant to ease morning sickness could damage the brain of a fetus, scientists who studied rats have warned.

Between 2002 and 2014, the rates of women using cannabis during pregnancy spiked by 62 percent in the U.S., and marijuana is the psychoactive drug used most commonly by pregnant women, according to the researchers at Auburn University, in Alabama. Expectant mothers turn to the drug because it can alleviate the symptoms of morning sickness.   

As more U.S. states move to legalize the drug and the stigma surrounding its use falls away, scientists wanted to investigate its potential harm to fetuses.

Past studies have indicated that coming into contact with cannabis in the womb could change how the brain’s networks develop, and could cause cognitive and behavioral problems in children “leading to a long-lasting effects on adult behavior,” the studies concluded.

In this new study, the researchers looked at how cannabis might affect the hippocampus: the part of the brain involved in memory and learning. They did this by exposing pregnant female rats to a synthetic chemical that acts similarly to cannabis at 2 milligrams/kilograms, until their young were born. The dose was comparable to an expectant mother using moderate to high amounts of cannabis. 

The brain connections in the baby rats exposed to synthetic cannabis in the womb were found to be reduced when compared with the rats that didn’t encounter the drug. The rats also underwent behavioral tests. 

A protein called neural cell adhesion molecule, which helps to maintain neural connections, was reduced in the cannabis-dosed rates. This could explain the observed learning and memory problems, the authors wrote. 

The team hopes the work could one day lead to treatments for children whose learning and memory has been damaged by marijuana use, boosting levels of NCAM.

Priyanka Das Pinky, a graduate student at Auburn University who co-authored the study, said in a statement: “Based on our research and the previous existing findings in the field, it can be said that using marijuana during pregnancy would not be a wise choice.

“However, it is also notable that the observed effect in the offspring can vary according to their age and according to the trimester during which they were exposed to the drug as well as dose and route of administration of the drug.”

The work will be presented at the American Society for Pharmacology and Experimental Therapeutics annual meeting during the 2019 Experimental Biology meeting. The work has therefore not been published in a peer-reviewed journal.

Pinky commented: “It is still very early to come up with a conclusion about the possible safe use of marijuana during pregnancy. More research is needed to evaluate the exact mechanism by which NCAM and/or its active form is modulating cellular effects while focusing on target-specific drug development for amelioration of the observed cognitive deficits.”

Ian Hamilton of the Department of Health Sciences at the University of York, U.K., who was not involved in the research, told Newsweek: “I am surprised to see the reported long-term impact on behavior and development this exposure to synthetic cannabis had.

“There are several potential limitations to this research that would need further exploration. First, this is an animal study: Although rats are often used in this type of investigation, we need to be careful in assuming these results would be mirrored in humans, particularly when it comes to behavioral outcomes which could be significantly different in humans, they may be worse or there might be no impact on behavior.”

Addressing drug use in pregnancy more broadly, he continued: “The safest option is for pregnant women to avoid all psychoactive drugs during pregnancy, including alcohol, which accounts for the greatest harm to unborn fetuses.

Hamilton argued there was a danger that people believe that cannabis is entirely safe, partly because some may perceive legislative changes as authorities’ endorsement of the drug. 

Last year, a separate study suggested using cannabis could damage the memory of adolescents. Teenagers and young adults who used cannabis regularly saw their memory power boosted a month after quitting. The findings were published in the Journal of Clinical Psychiatry.

Last modified: May 17, 2019