New research has shown that while women in the US have cut back on alcohol and cigarette use during pregnancy in recent years, they have increasingly shifted to another vice—cannabis.
In a research letter published this week (Nov. 6) in JAMA Pediatrics, a group of medical practitioners from Washington University’s School of Medicine in St Louis found that between 2002 and 2016, alcohol and cigarette use by US pregnant women decreased, but cannabis use rose.
The researchers used data from the Substance Abuse and Mental Health Services Administration’s National Survey of Drug Use and Health to track changes in alcohol, cigarette, and cannabis use during pregnancy from 2002 to 2016 among women between the ages of 18 and 44. They found that in 2016, amongst a sample size of almost 13,000 women, 8.43% reported having consumed alcohol in the previous 30 days, 10.34% reported having smoked cigarettes, and 4.98% reported having consumed cannabis. In 2002, those proportions were 9.59%, 17.5%, and 2.85%, respectively.
The SAMHSA surveys included data for women aged 15 to 18, but the researchers excluded that age category in their report because they wanted to focus on adult women.
The decline in alcohol and cigarette use during pregnancy is encouraging, but perhaps not surprising, given that an extensive public health campaign has aimed to educate women about the developmental risks of consuming both during pregnancy. When a pregnant woman drinks, the alcohol passes directly from her blood to the baby through the umbilical cord. High levels of alcohol consumption increases a woman’s risk of miscarriage or stillbirth and can lead the baby to develop a range of lifelong physical, behavioral, and intellectual disabilities known as fetal alcohol spectrum disorders.
When a woman smokes cigarettes while pregnant, she can also harm her baby. Cigarette use increases the risk of premature birth, certain birth defects like cleft palate, and infant death. Smoking can also impact the placenta, the source of the baby’s food and oxygen during pregnancy.
Cannabis enjoys a reputation for being more “natural” or healthier than cigarettes or alcohol. But earlier this year, in response to its legalization in some US states and in Canada, the American Academy of Pediatricians (AAP) raised concerns about how little we know about the impact of cannabis use on pregnant women and their babies.
To that end, the AAP released guidelines on cannabis use during pregnancy or while breastfeeding. They state that women who smoke cannabis during pregnancy are more likely to develop anemia, and that infants exposed to cannabis in the womb are more likely to be born underweight and to need to be admitted to an intensive care unit after birth. However, as the AAP explains, studies that measure the impact of cannabis use on pregnancy are flawed. They mostly rely on self-reported use, which means that women might be encouraged to underestimate their use. They are typically not adjusted for other lifestyle risk factors, like cigarettes or alcohol. And, because of ethical concerns, it’s impossible to conduct a randomized control trial that would answer these questions—a common obstacle when researching pregnancy.
While little is known about the overall impact of cannabis use during pregnancy and breastfeeding, the best available evidence tells us that prenatal exposure may put a baby at risk of short- and long-term developmental and behavioral consequences. That’s why the AAP advises all young women “that if they become pregnant, marijuana should not be used during pregnancy.”
Read more from our series on Rewiring Childhood. This reporting is part of a series supported by a grant from the Bernard van Leer Foundation. The author’s views are not necessarily those of the Bernard van Leer Foundation.