FRIDAY, Feb. 10, 2023 (HealthDay News) – New research links cannabis use in the first trimester of pregnancy to poor outcomes, closely related to functioning of the placenta.

This is important information given that more U.S. states are legalizing marijuana for recreational use, researchers said. The study findings were presented Thursday at a meeting of the Society for Maternal-Fetal Medicine, in San Francisco and online.

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

“With recreational marijuana use becoming legal in more states, we need better data because patients are interested in understanding the risk of cannabis use in pregnancy so they can make an informed decision,” Metz said in a meeting news release.

For the study, her team analyzed urine samples collected as part of major research project involving more than 10,000 of women due to give birth for the first time. Of those, data from more than 9,200 women in their first trimester of pregnancy was included.

About 540, or 5.8%, tested positive for marijuana. That meant they most likely used cannabis in the first six to 14 weeks of their pregnancy.

Using cannabis early in pregnancy was associated with several adverse outcomes, including poor fetal growth, stillbirth and an increased risk of developing high blood pressure during pregnancy, researchers found.

During pregnancy, the placenta provides the fetus with oxygen and nutrients, removes harmful waste and carbon dioxide, and produces hormones that help a baby grow. Medicine, drugs, alcohol and nicotine can transfer from a woman’s bloodstream to her fetus through the placenta.

The researchers now hope to examine ongoing cannabis use during pregnancy and whether the window of exposure matters.

The study was recently published in the American Journal of Obstetrics & Gynecology.

More information

The U.S. Department of Health and Human Services has more on having a healthy pregnancy.

SOURCE: Society for Maternal-Fetal Medicine, news release, Feb. 9, 2023