MONDAY, Dec. 19, 2016 (HealthDay News) -- Marijuana use by pregnant women in the United States is up significantly since the early 2000s, a new study finds.
Researchers looked at national data from women ages 18 to 44. They found the rate of past-month marijuana use among pregnant women went up from 2.4 percent in 2002 to nearly 3.9 percent in 2014. That's an increase of 62 percent, the researchers said.
Human and animal studies suggest that marijuana use during pregnancy may be associated with low birth weight and impaired neurodevelopment in babies, the researchers noted.
Younger women were most likely to have used the drug during the past month, the study found. In 2014, 7.5 percent of women ages 18 to 25 had used pot in the past month. For women between 26 and 44, only 2.1 percent had used pot in the past month.
More pregnant women (11.6 percent) said they'd used marijuana during the past year in 2014.
There were also increases in marijuana use among non-pregnant women of reproductive age. In 2014, 9.3 percent said they'd used pot in the past month. Sixteen percent said they'd used the drug during the past year.
The study was published online Dec. 19 in the Journal of the American Medical Association.
"These results offer an important step toward understanding trends in marijuana use among women of reproductive age," researchers Deborah Hasin, Qiana Brown and their colleagues wrote. Hasin and Brown are from Columbia University in New York City.
"Although the prevalence of past-month use among pregnant women [3.85 percent] is not high, the increases over time and potential adverse consequences of prenatal marijuana exposure suggest further monitoring and research are warranted," they added.
The researchers also suggested that doctors screen and counsel pregnant women and women contemplating pregnancy about marijuana use to ensure the best health for mother and baby.
Another study in the same issue of JAMA looked at medical marijuana use among Americans. Researchers reviewed 2013-2014 national data. They found that 13 percent of adults 18 and older said they used marijuana in the past year.
Ninety percent said their marijuana use was nonmedical only. Just over 6 percent said they used the drug for medical purposes. Combined medical and nonmedical use of pot was just under 4 percent, the study showed.
This study was written by Dr. Wilson Compton, from the U.S. National Institute on Drug Abuse, and colleagues. They found that among medical marijuana users, 79 percent lived in states where medical marijuana was legal. The rest of the users, 21 percent, were in states where medical pot isn't legal. That finding suggests that doctors might recommend medical marijuana to patients even if it's not legal in their state, the researchers said.
The March of Dimes has more on marijuana and pregnancy.