It’s becoming more common for pregnant women to use Marijuana during pregnancy, and a new study suggests one reason for the trend: Some pregnant women may be using marijuana to self-medicate symptoms of morning sickness.

The researchers found that pregnant women with severe nausea and vomiting in their first trimester had nearly four times greater odds of using marijuana in pregnancy, compared with pregnant women who didn’t experience morning sickness. And women with mild nausea and vomiting in pregnancy had two times greater odds of using marijuana, compared with women who didn’t have these symptoms.

Marijuana and morning sickness

In recent years, the percentage of pregnant women who report using marijuana has increased, from about 2.4 percent in 2002 to nearly 4 percent in 2014, according to a 2017 study. However, the reason behind the rise is unclear, and one hypothesis is that pregnant women are using marijuana to treat symptoms of morning sickness. However, few studies have looked at the link between marijuana use in pregnancy and symptoms of morning sickness.

In the new study, the researchers analyzed information from more than 220,000 pregnant women in northern California. These women filled out a survey about their substance use and provided urine samples in their first trimester for drug screening. The researchers also examined the participants’ medical records, looking for diagnoses of mild or severe morning sickness

Among the women with severe morning sickness, 11.3 percent used marijuana, compared with just 4.5 percent of women with no reported symptoms of morning sickness. Marijuana use was also higher among women who had mild morning sickness, with about 8.4 percent of those in this group using marijuana.

It’s important to note that the study found only an association between marijuana use and symptoms of nausea and vomiting in pregnancy. Although the results suggest that pregnant women may be using the drug to self-medicate for these symptoms, the study cannot rule out other possible explanations for the findings. For example, doctors could be diagnosing nausea and vomiting in pregnancy more frequently in women who use marijuana, or marijuana may be contributing to symptoms of nausea and vomiting in pregnancy, the researchers said.

Still, the findings suggest that pregnant women with nausea and vomiting should be screened for marijuana use and educated about safe and effective treatments for morning sickness, the researchers said.

Pot during Pregnancy

Marijuana use during pregnancy may be harmful for babies: Some studies have found a link between marijuana use in pregnancy and health problems in newborns, including low birth weight, according to the Centers for Disease Control and Prevention (CDC). Research also suggests that marijuana use during pregnancy could have long-term neurological effects: For example, some studies have found that children exposed to marijuana in the womb are at greater risk for attention and behavior problems, compared with babies not exposed to marijuana. The American College of Obstetricians and Gynecologists recommends that pregnant women not use marijuana.