CU study to lay foundation for marijuana’s impact on moms-to-be

Capturing exposure through umbilical cord sampling, new self-reporting approaches
March 20, 2016
Dr. Torri Metz
Dr. Torri Metz, a perinatologist, is leading the study with an assist from substance use disorder expert Ingrid Binswanger.

You can’t manage what you can’t measure, so the saying goes. You can’t study what you can’t measure, either, which is a problem for those trying to understand how using marijuana during pregnancy might impact the health of pregnant moms and the babies they deliver.

There have been studies that found babies born of mothers who used marijuana, which crosses the placenta, to be slightly shorter and weigh less. Marijuana use has also been linked to preterm birth and stillbirth. Other studies have been inconclusive. But nearly all them relied heavily on self-reporting – questionnaires in which women admitted (or didn’t admit to) using marijuana.

Self-reporting, at least as traditionally done, introduces serious uncertainty as far as what, if anything, are the effects of actual drug use. For an epidemiological study attempting to determine a drug’s actual impact, that’s a big deal. Marijuana legalization increases use, as Colorado data have shown, so one can expect the effects of marijuana use during pregnancy – whatever they are – to become an area of greater interest as more and more states follow Colorado’s lead. There is therefore a pressing need for a more solid foundation for future studies, Torri Metz, MD, MS, a Denver Health Medical Center perinatologist and University of Colorado School of Medicine assistant  professor, believes. She’s doing something about it.

Trust, but verify

Metz, who sees patients and delivers babies at University of Colorado Hospital and Denver Health, is launching a one-year study that aims to use an emerging drug-sampling technology and a new approach to marijuana-use self-reporting to prepare the ground for studying marijuana’s impact on moms-to-be and their babies.

“If we can establish the best way to ascertain marijuana exposure during pregnancy, I think it opens the door for a lot of important, impactful studies,” Metz said. “It allows us to look at outcomes of moms and babies with prenatal marijuana exposure in a really methodologically sound way.”

About 10 percent of moms delivering at UCH admitted to marijuana use in the past 30 days.
The study is being paid for by a $20,000 Colorado Clinical and Translational Sciences Institute Child Maternal Health Pilot Program grant. It hinges on developing a new tool for women to self-report their marijuana use during pregnancy. The results will be compared against a postpartum test capturing marijuana use in the second and third trimesters based on an umbilical cord homogenate assay.

The study will involve 100 randomly selected women at UCH and Denver Health who Metz will approach within two days of delivery. They’ll use the self-reporting tool and consent to have a six-inch section of umbilical cord – which is routinely collected anyway – tested for the study. ARUP Laboratories in Salt Lake City, Utah, will do the marijuana testing.

Rethink the survey

Co-investigator Ingrid Binswanger, MD, MPH, a CU associate professor of Internal Medicine who specializes in researching substance use disorders, will help develop the self-reporting tool, Metz says. Coming into play will be approaches that include letting patients record their answers on a device rather than saying them aloud to someone face-to-face, providing federal certificates of confidentiality (preventing any information they give for research purposes to be used in litigation), and training staff to help patients feel more comfortable. The tool will also assess women’s attitudes and beliefs about marijuana, Metz added.

“I do think there’s a perception of safety, and it’s hard to know how that’s influenced by the legalization of marijuana,” she said.

Women she sees in clinic have told her that they’ve taken the drug to subdue nausea and boost appetite, Metz said. A preliminary study she conducted with Binswanger found about 10 percent of pregnant women at UCH and Denver Health have admitted using the drug in the past 30 days. A retrospective look at charts for self-reported and urine-tested marijuana use among 743 women delivering at UCH before legalization in 2013 and the year after found self-reporting of marijuana use jumped from 4.3 percent to 7.5 percent, and that, among those who had their urine drug-tested, self-reporting more closely jibed with the urine test results. That hints that women are more likely to admit to marijuana use during pregnancy when the drug is legal.

How marijuana affects babies and moms hinges on an understanding of actual cannabis consumption during pregnancy.
Part of that may be that the social stigma of using the drug wanes, Metz said. It’s certain that marijuana is still viewed differently than alcohol, whose damage to babies born with fetal alcohol syndrome is well-documented. Of course, Metz said, “Just because it’s a plant doesn’t mean it’s safe for you. Tobacco is a great example.”

Once the new study’s results are in hand, Metz hopes to apply for grants to fund research on marijuana’s impact on preterm birth, stillbirth, fetal growth and hypertensive diseases during pregnancy.

“Colorado is very unique,” she said. “It’s one of the first states with full legalization, so it’s the ideal place to do these sorts of studies.”

About the author

Todd Neff has written hundreds of stories for University of Colorado Hospital and UCHealth. He covered science and the environment for the Daily Camera in Boulder, Colorado, and has taught narrative nonfiction at the University of Colorado, where he was a Ted Scripps Fellowship recipient in Environmental Journalism. He is author of “A Beard Cut Short,” a biography of a remarkable professor; “The Laser That’s Changing the World,” a history of lidar; and “From Jars to the Stars,” a history of Ball Aerospace.