This article by By NICHOLAS BAKALAR of the NY Times
When pregnant women are asked if they smoke, almost a quarter of the smokers deny they have the habit. Using data from the National Health and Nutrition Examination Survey conducted from 1999 to 2006, researchers writing online in The American Journal of Epidemiology report that 13 percent of 994 pregnant women, and almost 30 percent of 3,203 nonpregnant women of reproductive age, were active smokers. (Rates among these women, 20 to 44 years old, are higher than rates for the general population of women.)
Among pregnant smokers, 23 percent reported that they did not smoke, despite high blood levels of cotinine, a biological indicator of tobacco exposure, that showed they did. More than 9 percent of the nonpregnant smokers also lied about it.
The authors acknowledge that cotinine levels can be increased by secondhand smoke, and that the exact blood level of cotinine that indicates smoking in pregnant women is not known. But pregnant women metabolize cotinine faster than nonpregnant women, so their smoking rate may actually have been underestimated.
The lead author, Patricia M. Dietz, an epidemiologist with the Centers for Disease Control and Prevention, said that the deceit probably stemmed from embarrassment. “Smoking has been stigmatized,” she said. “They feel reluctant to be chastised.” But concealing the addiction is not the answer, she said — quitting is. And, she added, “it’s never too late to quit.”