A new study finds that women are increasingly smoking pot during pregnancy.

FOX's Pat O'Neill has the details:

An analysis of government surveys finds that almost four percent of pregnant women in 2014 in the U.S. said they'd recently smoked marijuana often for morning sickness. That's up from 2.4 percent 12 years earlier.

Researchers say it raises concerns because of evidence, linking pot use to low birth rates, along with higher risk of anemia in newborns and other problems.

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

Another study in the journal found that almost 10 percent of adult marijuana smokers have used it at least partly for medical reasons and 20 percent of those live in states where medical marijuana is not legal.

Pat O'Neill, FOX News.