A neonatal care unit. Photo by David Quitoriano via Flickr

Babies born to mothers who consistently use cannabis are more likely to experience health problems, according to findings published Thursday by UC San Diego researchers.

The study, from UCSD’s Wertheim School of Public Health and Human Longevity Science, examined nearly five million live births in California from 2001-12. Over that period, diagnoses of an ailment, cannabis use disorder, rose.

The disorder is defined as continued cannabis use despite consequent, clinically significant impairments. Not all people who use marijuana meet the criteria for cannabis use disorder, though the study’s authors stated the actual incidence of cannabis use disorder is likely higher than reported numbers.

The journal Addiction published the findings of the study, funded by the National Institute on Drug Abuse, part of the National Institutes of Health.

Of the 4.83 million births studied, 20,237 women were diagnosed with the disorder, according to UCSD researchers.

They found that those women’s babies were more likely to be born preterm, have a low birth weight and be small for their gestational age. The factors can require greater or more intense medical care or lead to other health issues.

Mortality risks was also greater for those babies, though the researchers said those instances were rare.

Yuyan Shi, an associate professor at the Wertheim school, and one of the study’s authors, said: “Because we are looking only at medical records, there is a lot we don’t know about the mothers and infants in this study, but our analysis supports the recommendation that health professionals screen for and address cannabis use disorders in their pregnant clients – to protect both their health and potentially the health of their infants.”

According to UCSD, it is not currently standard practice during pregnancy health care to screen for cannabis use or related disorders, though marijuana is the most commonly used illicit drug by pregnant women to self-treat depression, anxiety, stress, pain, nausea and vomiting, often during the first trimester.

It is also not a standard of care to provide counsel on the lack of safety data around cannabis use during pregnancy.