One in 10 expectant mothers aged 18 to 44 drink alcohol during their pregnancies, and many of them binge-drink, a study released on Thursday by the U.S. Centers for Disease Control and Prevention found.
A third of the pregnant women who drank reported consuming four or more drinks in rapid succession, known as "binge drinking," according to the study based on a telephone survey.
The frequency of the binge drinking was higher in pregnant women than among those who were not pregnant, surprising the study's lead author, Cheryl Tan.
"Any alcohol use during pregnancy is associated with an increased risk of birth defects and developmental disabilities," she told Reuters.
One possible explanation is that women who binge-drink during pregnancy are more likely to have alcohol addiction issues, the study noted.
Alcohol use during pregnancy was highest among women aged 35 to 44, with 18.6 percent reporting that they had consumed at least one alcoholic beverage in the previous 30 days, researchers found.
The study compared telephone survey data from 8,333 pregnant women and 198,000 non-pregnant women from all 50 states and the District of Columbia in 2011-2013. About half of the non-pregnant women surveyed said they drank alcohol.
Women were surveyed over land line telephones and cell phones, making the findings difficult to compare to earlier studies involving only land lines, Tan added.
College graduates were twice as likely to drink during pregnancy as non-graduates, the study found, possibly because of higher discretionary income or because alcohol consumption was considered "socially acceptable" during their college years.
Non-married pregnant women were 4.6 times more likely to binge drink than married pregnant women, the study found.
The study should be a call to action for pregnant women, who often receive "mixed messages" in the media about whether it is safe to drink during pregnancy, Tan said.
She called for doctors to screen pregnant women for alcohol use and try to persuade them to stop drinking.
"It's really important to remember that there is no safe amount, no safe time and no safe type of alcohol to drink during pregnancy," she said.