SOUTH PORTLAND – The nation’s top expert on pregnancy and smoking among women who receive Medicaid urged health professionals in Maine to convince women that smoking during their pregnancies is dangerous.

Cigarette smoke contains about 4,000 chemicals, including nicotine, which kill brain cells, said Richard Windsor, chairman of the department of prevention and community health at the George Washington Medical Center. Smoking during pregnancy can lead to low birth weights in babies, premature births and sudden infant death syndrome.

“I know you fully appreciate the risk,” he told doctors, nurses and public health officials Wednesday at the annual meeting of the American Lung Association of Maine, “but I’m not fully certain the pregnant smoker, whether on Medicaid or not, does.”

Smoking during pregnancy is an epidemic among low-income women in Maine. Almost 40 percent of Medicaid recipients continue to smoke during their pregnancies, compared with 10 percent of pregnant women who are not on Medicaid.

Windsor, who acknowledged that quitting can be difficult, outlined a program he developed that seems to be helping pregnant women in Alabama to kick the habit.

Women in an experimental group watched a 10-minute “Commit to Quit” video and were given a 32-page self-help guide developed with the assistance of other pregnant smokers. The women received a brief counseling session and they had to commit to quitting within the next seven days. Researchers also checked the levels of cotinine, a breakdown product of nicotine, in the women’s saliva to make sure they were being truthful about quitting.

The results were impressive: 18 percent of the women in the experimental group quit smoking for the duration of their pregnancy, compared with only 8 percent in a control group.

Windsor said the program works because it sends women a clear, strong message that quitting is essential and there are specific tools they can use to help them end their smoking habit.

“Women who smoke have a generalized notion of risk,” he said. “They’re not quite as convinced, so we’ve got to spend more time, more forcefully, more directly, more assertively, saying ‘OK, this is an important problem.”‘