FILE - This Sept. 15, 2015 file photo shows marijuana plants with their buds covered in white crystals at a medical marijuana cultivation center in Albion, Ill. U.S. women are increasingly using marijuana during pregnancy, sometimes to treat morning sickness, new reports suggest. Though the actual numbers are small, the trend raises concerns because of evidence linking the drug with low birth weights and other problems. (AP Photo/Seth Perlman, File)

CHICAGO | U.S. women are increasingly using pot during pregnancy, sometimes for morning sickness. That’s according to an analysis of annual U.S. government drug surveys.

Though the actual numbers are small, researchers and others say the trend raises concerns because of evidence linking the drug with low birth weights and other problems.

FILE - This Sept. 15, 2015 file photo shows marijuana plants with their buds covered in white crystals at a medical marijuana cultivation center in Albion, Ill. U.S. women are increasingly using marijuana during pregnancy, sometimes to treat morning sickness, new reports suggest. Though the actual numbers are small, the trend raises concerns because of evidence linking the drug with low birth weights and other problems. (AP Photo/Seth Perlman, File)
FILE – This Sept. 15, 2015 file photo shows marijuana plants with their buds covered in white crystals at a medical marijuana cultivation center in Albion, Ill. U.S. women are increasingly using marijuana during pregnancy, sometimes to treat morning sickness, new reports suggest. Though the actual numbers are small, the trend raises concerns because of evidence linking the drug with low birth weights and other problems. (AP Photo/Seth Perlman, File)
FILE – This Sept. 15, 2015 file photo shows marijuana plants with their buds covered in white crystals at a medical marijuana cultivation center in Albion, Ill. U.S. women are increasingly using marijuana during pregnancy, sometimes to treat morning sickness, new reports suggest. Though the actual numbers are small, the trend raises concerns because of evidence linking the drug with low birth weights and other problems. (AP Photo/Seth Perlman, File)

In 2014, almost 4 percent of pregnant women said they’d recently used marijuana. That’s up from 2.4 percent in 2002.

The study was published online Monday in the Journal of the American Medical Association.

A separate study in the same journal found that almost 10 percent of adult marijuana users in the United States have used it at least partly for medical reasons; 20 percent of these users live in states where medical marijuana isn’t legal.

Tagged: