A new study has found cannabis use during pregnancy to not be independently linked to adverse neonatal outcomes.
When used without tobacco or other drugs, cannabis use during pregnancy poses no significant risks on a newborn’s birth weight and preterm delivery, according to a new study published in Obstetrics & Gynecology.
A team of researchers, led by Dr. Shayna N. Conner of Washington University in St. Louis’ School of Medicine, reviewed 31 observational studies that examined the effects of maternal marijuana use on neonatal outcomes between 1982 and 2015. While the unadjusted data did show marijuana use during pregnancy to be associated with an increased risk of low birth rate (15.4 percent compared to 10.4 percent) and preterm delivery (15.3 percent compared to 9.6 percent), once the data was adjusted for tobacco use, there was “no statistically significant increased risk for low birth weight.”
“We found that maternal marijuana use during pregnancy is not an independent risk factor for low birth weight or preterm delivery after adjusting for factors such as tobacco use. There also does not appear to be an increased risk for other adverse neonatal outcomes such as [small for gestational age] and placental abruption once we account for other influencing factors,” the study reads.
The study’s findings are consistent with the results of a study from 2010, which was sponsored by the U.S. Centers for Disease Control and published in Drug and Alcohol Dependence. Using interview data from mothers who had delivered infants without birth defects between 1997 and 2004, the researchers found cannabis use to be not associated with low birth weight or preterm birth. Other studies, however, have shown cannabis use to slightly increase the risk of spontaneous preterm birth and a birth defect called anencephaly.
Dr. Conner and her team suggest in their study that the adverse neonatal outcomes reported in women who use cannabis during pregnancy is likely due to the result of coexisting use of tobacco and other confounding factors. She was sure to make note, however, that she doesn’t recommend using marijuana while pregnant.
“Any foreign substance that doesn’t directly benefit maternal or fetal health should be avoided,” Dr. Connor recently told NPR. However, she did point out that her study’s results indicate that public health dollars should be budgeted on preventing alcohol and tobacco, behaviors that have proven to independently cause birth defects and preterm delivery, rather than preventing cannabis use during pregnancy. Conner also noted that her team’s findings might give comfort to women who consumed cannabis before discovering they were pregnant.
With four states allowing legal adult marijuana use and five more states voting on recreational marijuana initiatives this November, the examination on cannabis’ effects on pregnant mothers and prenatal infants will likely become more important. A recent poll found that cannabis use is up nationwide, and according to the American College of Obstetrics and Gynecology, between 2 percent and 5 percent of women admit to using marijuana while pregnant.
Learn more about the studies that have been done on cannabis’ therapeutic effects by visiting our education page. Keep up with the latest studies examining cannabis and its effects by regularly visiting our news feed.