Recent research has shown that smokers are more likely to have mental-health problems than nonsmokers, and a new study says the same holds true for pregnant women.

A review of data on more than 1,500 adult women who took part in the 2001-2002 National Epidemiological Survey of Alcohol and Related Conditions found that 21.7 percent of pregnant women smoke, and 57.2 percent of smokers were classified as nicotine-dependent.

Bottom line: 12.4 percent of pregnant women are nicotine-dependent, Columbia University researchers said. And nicotine-dependent women were more likely than nonsmokers to meet the criteria for at least one mental disorder.

"Understanding that these co-morbidities exist may shed light on why some women are unable to abstain from smoking during pregnancy even though they understand the negative health impact for them and their unborn children," said National Institute on Drug Abuse Director Nora D. Volkow. "There is tremendous value in screening pregnant women who are unable to abstain from smoking for mental disorders -- to not only identify and treat those who have been undiagnosed but also to improve successful quit smoking attempts." 

The study was published in the April 2007 issue of the journal Obstetrics and Gynecology.