Cannabis use early in pregnancy associated with poor pregnancy outcomes

As more states legalize marijuana for recreational use, researchers are exploring the potential health effects of cannabis use during pregnancy.

In a new study that will be presented today at the annual meeting of the Society for Maternal-Fetal Medicine (SMFM), The Pregnancy Meeting™ – and published in the American Journal of Obstetrics and Gynecology -; researchers will reveal findings suggesting that cannabis use in the first six to 14 weeks of pregnancy is associated with poor pregnancy outcomes closely related to placental function.

The placenta plays an important role during pregnancy, including providing a baby with oxygen and nutrients, removing harmful wastes and carbon dioxide, and producing hormones that help a baby grow. Medications, drugs, alcohol and nicotine can be transferred from a pregnant woman’s bloodstream to the baby through the placenta.

Researchers analyzed urine samples collected during the Nulliparous Mothers-to-Be (nuMoM2b) study, a large, diverse multicenter cohort of pregnant people. Of the 10,038 nuMoM2b participants, researchers included data from 9,257 pregnant people in their first trimester of pregnancy.

After a drug screening for marijuana, the researchers found that 540 (5.8 percent) tested positive for marijuana, meaning those individuals were most likely to have used cannabis in the first six to 14 weeks of their pregnancy. The study found that cannabis use early in pregnancy is associated with adverse pregnancy outcomes related to the placenta, such as poor fetal growth, stillbirth and an increased risk of developing high blood pressure during pregnancy.

“We specifically wanted to look at cannabis use early in pregnancy, because that’s when the placenta is forming, and a lot of the information we currently have indicates that cannabis use affects the placenta,” said the study’s lead author, Torri D. Metz, MD, MS, a subspecialist in maternal-fetal medicine and an associate professor of obstetrics and gynecology at the University of Utah Health in Salt Lake City.

“As recreational marijuana use becomes legal in more states, we need better data because patients are interested in understanding the risk of cannabis use during pregnancy so they can make an informed decision.”

The next step, researchers say, is to look at continued cannabis use during pregnancy and whether “the window of exposure” matters.


Association for Maternal Fetal Medicine

Cannabis use early in pregnancy associated with poor pregnancy outcomes

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