Cannabis is the most widely used illicit drug in the United States, according to the National Institute on Drug Abuse. The 2016 National Survey on Drug Use and Health found that an estimated 24 million Americans ages 12 and older were using cannabis that year. This was the highest number of people found to be using cannabis in the preceding 14 years.
Known by many names-marijuana, weed, pot-cannabis has just as many methods of ingestion. It can be smoked and is available as an edible, elixir, and oil. The number of people with legal access to this drug has been steadily growing since California passed the first statewide laws allowing for the medical use of cannabis in 1996. Currently, 34 states plus the District of Columbia, Guam, Puerto Rico, and the U.S. Virgin Islands have passed laws that allow adults to use cannabis legally. The federal government continues to classify cannabis as a Schedule I substance.
One consequence of the greater availability of cannabis is a rise in the number of pregnant women using the drug. "Now that it is becoming legalized, people are more open about discussing it," said Leena Nathan, MD, who works in the obstetrics and gynecology department at UCLA Health in Westlake Village, California. "The most common reason for using it is that it helps with nausea and vomiting in the first trimester." In research published in the July 9 JAMA, Volkow and colleagues note that the prevalence and frequency of past-month cannabis use among pregnant women and adolescents ages 12 to 44 increased from 2002 to 2017. Use was higher during the first trimester compared with later trimesters.
"There are longitudinal studies that exposure in utero may have some issues, especially those that are neurobehavioral in nature," Nathan said. "There is no evidence-based research showing that it is safe in pregnancy, so why take a chance?"
DISTURBING TRENDS IN CANNABIS USE DURING PREGNANCY
Several studies have sought to estimate trends in usage during pregnancy, as well as the effect of prenatal use on neonatal outcomes. In one study published in JAMA in late 2017, researchers from Kaiser Permanente Northern California (KPNC) examined prenatal cannabis use from 2009 to 2016 using data from their health system, in which pregnant women and adolescents are screened via self-report and urine toxicology. The authors, led by Kelly C. Young-Wolff, PhD, MPH, a KPNC research scientist, found that cannabis use increased from 4% to 7% among a cohort of nearly 300,000 pregnant women and adolescents ages 12 and older. Notably, 22% of those younger than age 18 and 19% of those ages 18 to 24 screened positive for cannabis use in 2016.
In a follow-up study published the next year in JAMA Internal Medicine, Young-Wolff and colleagues examined the use of cannabis as an antiemetic during the same time period. They found that pregnant women who had mild or severe nausea and vomiting were significantly more likely to have used cannabis compared with women who didn't have these symptoms. Self-report or toxicology testing demonstrated a prevalence of cannabis use during the first trimester of 5.3% among 220,510 pregnant women and adolescents ages 12 and older. Prevalence more than doubled to 11.3% among those reporting severe nausea and vomiting and was 8.4% for those who had more mild symptoms.
"We hope the study findings can help alert clinicians to the fact that their patients with nausea and vomiting in pregnancy may be more likely to use cannabis," says Young-Wolff. "Given concerns about the risks of cannabis use in pregnancy, it is important that clinicians encourage women to abstain from using cannabis during the perinatal period."
ASSESSING DANGER TO THE FETUS
Just how dangerous is cannabis to a fetus? There are several challenges to assessing its effect, and study results have been mixed. The American College of Obstetricians and Gynecologists notes that cannabinoids can readily cross the placenta, and experimental models have shown that exposure could disrupt normal brain development and function. And in an August 29 advisory, the U.S. surgeon general warned that cannabis use in pregnant women can impact fetal brain development. A recent study by Corsi and colleagues in the July 9 JAMA looked at prenatal cannabis use and risk of adverse maternal and perinatal outcomes. In a cohort of 661,617 women and adolescents ages 15 and older-of whom 9,427 used cannabis-the researchers found a higher risk of preterm birth (occurring before the 37th week of pregnancy) among reported cannabis users compared with those who didn't use the drug during pregnancy (12% versus 6.1%). There was also a higher risk of small-for-gestational-age infants, placental abruption, transfer to the neonatal ICU, and a 5-minute Apgar score of less than 4. However, the authors conclude that cannabis use was also associated with a small but statistically significant protective effect for preeclampsia and gestational diabetes.
Cyndy Krening, MS, RNC-OB, C-EFM, a perinatal clinical specialist at Saint Joseph Hospital in Denver, explains that there are many difficulties associated with conducting such studies. "We can't ethically do a randomized controlled trial, and since cannabis is still considered a Schedule I drug, federally funded research is not allowed," she says. "Since cannabis users may also use tobacco, alcohol, and other substances, it can be very difficult to tease out the cannabis component." Observational and epidemiologic studies are frequently heavily confounded not only by polysubstance use but also by lifestyle factors, she notes.
In addition, women aren't always forthcoming about cannabis use. Even though cannabis use is legal in Colorado, for instance, there are still reporting laws. Using cannabis, like any controlled substance, while pregnant can be considered child abuse. "Some providers aren't asking about use because they don't want to know," says Krening. "And some patients aren't forthcoming because they don't want to risk being reported."
But the discussion about cannabis use is an important one. "As nurses, we are all about education, and that should include educating ourselves," Krening says. Nurses can obtain such education, she notes, by attending conferences and seminars or from their state health departments. In Colorado, for instance, she notes that the Department of Health offers health care providers clinical guidelines that include scripted talking points designed to facilitate discussions with patients about cannabis use during pregnancy.
ALCOHOL USE IS STILL A PROBLEM
Although cannabis use during pregnancy has received much attention in recent years, it's not the only substance of concern. A study published in the April Morbidity and Mortality Weekly Report highlights the continuing problem of alcohol use during pregnancy. Researchers estimated that 11.5% of pregnant women ages 18 to 44 were currently drinking (having at least one drink in the previous 30 days), and 3.9% were binge drinking (having at least four drinks on one occasion in the past 30 days) between 2015 and 2017.
"Since the 1970s, research has shown that alcohol is a potent teratogen to the fetal brain at every stage of development, and we now know there is no protection at any stage of gestation," says Catherine Ruhl, MS, CNM, director, patient education and outreach for the Association of Women's Health, Obstetric and Neonatal Nurses. The knowledge has changed, and health care professionals need to obtain updated information, Ruhl notes. "Nurses and other providers understand fetal alcohol syndrome but may not be as up-to-date on fetal alcohol spectrum disorder." Fetal alcohol syndrome is the extreme end point of a collection of disorders stemming from prenatal alcohol use, which are now termed fetal alcohol spectrum disorders. "These children do not have the dysmorphic facial features and characteristics of full-blown fetal alcohol syndrome," according to Ruhl. "Instead, they were affected to some degree in utero by alcohol and may have ended up being misdiagnosed as having autism, ADHD [attention deficit-hyperactivity disorder], or another problem, even though they never quite fit the diagnosis."
Providers should be screening everyone about alcohol and discussing safe limits. "We need to see if someone is at risk, without being punitive or judgmental," says Ruhl. "Health care professionals need to be aware that many people use alcohol to cope, and this occurs across all social strata."
Ideally, alcohol use should be discussed with women before they become pregnant, she added, or at least as early as possible during prenatal care.-Roxanne Nelson, BSN