Using marijuana during pregnancy can cause low weight in newborns: study

Women who use marijuana during pregnancy may be putting their babies’ health at risk, and the risk increases as use increases, a new study suggests.

An analysis of data from more than 9,000 expectant mothers across the United States revealed that cannabis exposure during pregnancy is associated with a increased risk of unhealthy outcomes, especially low birth weight in newborns.

Additionally, the more cannabis moms-to-be use, the greater the risk, according to the report published Tuesday in the Journal of the American Medical Association.

“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 associate professor at University of Utah Health.

“And the risk increased with increasing use. This demonstrates that “It is better not to use cannabis during pregnancy”he added.

Cannabis and the functions of the placenta

Researchers looked at the impact of marijuana use on a combination of potential negative outcomes (low birth weight, medically induced preterm birth, stillbirth, and pregnancy-related high blood pressure in expectant mothers) and found that the risk increased by nearly 30 % in those who used cannabis during pregnancy.

“The reason we combined them is that they are all related to placental function,” Metz said.

Previous research in both animals and humans found that exposure to cannabis It can negatively affect the placenta, which is the source of nutrients and oxygen for the developing fetus.

When the researchers looked at those results individually, they found a 50% increase in the risk of low birth weight.

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There was also an increased risk of stillbirth, neonatal intensive care admission, and neonatal complications and deaths, but those associations were not statistically significant, meaning the result could simply be due to chance.

The researchers looked at the impact of marijuana use on a combination of potential negative outcomes.Anusak Laowilas / NurPhoto via Getty Images

Babies identified as having low birth weight were smaller than 95% of other babies, Metz said, adding that they could be at risk for other negative health outcomes later in life, such as obesity.

The new study reinforces the findings of a 2021 study that reported health problems in children whose mothers used heavy cannabis during their pregnancies.

More states legalize recreational use

The findings come as more states have legalized marijuana for recreational use.

To take a closer look at the possible impact of marijuana use during pregnancy, Metz and her colleagues turned to data from a previous study that followed expectant first-time mothers during their pregnancies.

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The women in that study were recruited between 2010 and 2013, and all had provided urine samples in each of the three trimesters. The samples were frozen and stored, allowing Metz and her colleagues to document how much and during which trimesters marijuana had been used during the pregnancies of the 9,257 expectant mothers in the study.

The researchers were also able to document the use of tobacco and other drugs and took them into account in the analysis.

One of the “most notable features” of the new study is that researchers were able to identify and measure how much, if any, cannabis the expectant mothers had used during their pregnancies, said Ziva Cooper, a UCLA professor and director of its Center of Cannabis and Cannabinoids.

“Another important feature is that they looked at and compared use in the first trimester with use throughout pregnancy: one-third of women who used cannabis at first stopped using it, while the other two-thirds continued,” said Cooper, who He was not involved in the new study. “And they found different neonatal outcomes.”

A key finding was the correlation between the amount of marijuana consumed and the level of risk for the babyCooper said. Greater use was related to a higher level of risk.

Limitations of the study

Still, the study has limitations, including a lack of information about why the expectant mothers used cannabis and exactly when they smoked or consumed it, Cooper said. Surveys have shown that women often say they use cannabis to help them cope with morning sickness, she added.

“The moral for women is that “There are still many unknowns when it comes to the risks related to cannabis use during pregnancy.”Cooper said. “It is encouraging news that the risks were associated with continuous use but not with use during the first trimester.”

Dr. Silvia Martins, professor of epidemiology and director of substance use epidemiology at Columbia University Mailman School of Public Health, said heavy marijuana use in the first trimester would likely be concerning.

More research needs to be done in this area, said Martins, who was not involved in the new study.

“And, of course, we need a larger number of women to be asked detailed questions to be able to determine the most important adverse effects and exactly what doses of cannabis are problematic,” she said.

A study with more women could shed more light on complications that were not statistically significant in this study, Martins said.