Significant numbers of marijuana users continue use during pregnancy mistakenly thinking it's safe

Marijuana exposure during pregnancy is associated with seven adverse outcomes, including preterm deliveries, more neonatal intensive care unit (NICU) admissions, decreased birth weight and more. A large metanalysis on the topic was conducted because findings about the risks of marijuana use during pregnancy across earlier studies have been inconsistent, according to Dr. Greg Marchand, director of the Marchand Institute for Minimally Invasive Surgery in Mesa, Arizona. He was lead author of a study published in JAMA Network Open. Rates of self-reported marijuana use during pregnancy generally range from 2%-to-5%, although this rate could be an underestimate due to underreporting. Some studies found that the rates are as high as 15%-to-28% in populations of young women who are less advantaged socioeconomically and living in urban areas. There can be cultural differences too. Read: Requests for caesarean birth brushed aside, despite guidelines to respect maternal choices Remarkably, 34%-to-60% of individuals who use marijuana keep using it during pregnancy, with many believing it is safe, Dr. Marchand said. “Intoxication lasts only hours, but it’s half-life when looking at all the metabolites is much longer, so it’s going to be detectable in the blood for at least a few days, and isn’t really eliminated from the fatty stores of the body for up to 30 days,” he said. The study noted that delta-9-tetrahydro-cannabinol crosses the placenta. Plus, “cannabinoid receptors are present in the central nervous system of a developing fetus at the beginning of the second trimester. Exposure to exogenous cannabinoids may be associated with changes in the prefrontal cortex and theoretically with its development and function.” The systematic review and meta-analysis was designed to investigate the association of marijuana use during pregnancy with neonatal outcomes. Researchers included interventional and observational studies which included pregnant women exposed to marijuana and compared them with pregnant women who were not exposed. The studies had to report at least one of several pre-defined neonatal outcomes. A total of 16 observational cohort studies encompassing 59,138 patients were included in the analysis. Analyses found that marijuana use was strongly associated with seven adverse outcomes when compared to non-users. These included a greater risk of low birth weight; small for gestational age; lower fetal weight; significantly smaller neonatal head circumference; increased rates of preterm delivery; more NICU admissions, and an increased mean Apgar scores at one minute, But, when compared to women not exposed to marijuana during pregnancy, there were no significant differences in mean Apgar score at five minutes, and no significant difference in the rate of occurrence of Apgar scores less than seven at five minutes of life. There also appeared to be no significant differences in infant length between the two groups, nor in mean gestational age at time of delivery. “The data was a little stronger than we expected, especially the connection to preterm birth. The lower birth weight and NICU admissions I was expecting—just based on the logic of the smoke choking out the oxygen in the mother's lungs,” Dr. Marchand said. Many studies didn’t include sufficient details on dose or frequency of marijuana use. “There wasn’t enough data on that to show a meaningful difference. Personally, I would encourage patients to use as little marijuana as possible to get relief from their symptoms (such as nausea and anxiety), and never to smoke marijuana,” he said. The data don’t include concomitant tobacco as a confounding factor in adverse neonatal outcomes, but in general it’s known that about 5% of North American women smoke cigarettes during pregnancy. “All of the studies were looking at smoked marijuana. I think the jury is still out on whether inhaled vapers or consumed marijuana will have the same effect. As a result, if a woman cannot give up marijuana during pregnancy, I'd recommend vapers or edibles. At least one recent study found cannabis use during pregnancy went up by 25% during the pandemic. Meanwhile, in Canada, a review Canadian Family Physician stated that that cannabis is the most commonly used illicit drug during pregnancy. They cautioned that women using cannabis in pregnancy are more likely to use alcohol, tobacco, and illicit drugs, which might have additive or synergistic effects. As well, many users during pregnancy have been found to be underweight, have lower income and education status, and are less likely to take folic acid. Additionally, cannabinoids readily cross the placenta, and also appear in human breast milk, resulting in both fetal and neonatal exposure. SOGC cautions against cannabis use during pregnancy The Society of Obstetrics and Gynecology of Canada (SOGC) warns against cannabis use during pregnancy. A statement on their website said “a growing body of medical research which suggests that the use of cannabis during pregnancy may be associated with the risk of low birth weight, preterm labour, stillbirth and may also negatively impact the developing baby’s brain. “There is already strong evidence showing that cannabis is not good for the developing teen brain. Why would we think this wouldn’t be the case for the fetal brain?” said Dr. Jennifer Blake, in the statement. She is the SOGC CEO. “Current research indicates that cannabis has the potential to cause lifelong harm to a developing fetus in terms of memory function, hyperactive behaviour and an increased risk of anxiety or depression. Why risk it?” There was an overall jump in female cannabis consumption from seven percent in 2013 to 10% in 2015 and a concern that these numbers will jump further. The statement noted “when cannabis was first legalized in Colorado in 2014, there was a 23% spike in emergency hospital visits for cannabis-related illnesses in teens ages 13 to 20.” Recreational cannabis use was legalized in Canada in 2018. “Our recommendation is to avoid cannabis during pregnancy and seek other alternatives to reduce nausea. And for women who use cannabis for medical reasons, we advise them to talk to their health care provider,” said Dr. Blake.

Significant numbers of marijuana users continue use during pregnancy mistakenly thinking it's safe

Register for free access or login.

Related Topics