THURSDAY, June 10 (HealthDay News) -- Women who quit smoking before they get pregnant may save their babies' lives, says a new study of more than 3 million births.

Looking at the data, researchers from the U.S. Centers for Disease Control and Prevention found that smoking during pregnancy resulted in 5 percent to 8 percent of all premature births and 13 percent to 19 percent of full-term babies with a low birth weight.

Researchers also found that 5 percent to 7 percent of deaths among the premature infants -- and 23 percent to 34 percent of deaths caused by SIDS -- could have been prevented if the mother had not smoked.

The CDC researchers examined data on 3.3 million births of single babies across the country (with the exception of California) during 2002. About 11.5 percent (386,000) of those babies had mothers who smoked during pregnancy.

If all women quit smoking during pregnancy, health care costs in the United States could be reduced by about $232 million a year and there would be improved overall health for mothers and babies, according to the researchers.

"We know that about half of women quit when they find out that they are pregnant, but a lot of women are still smoking during pregnancy," lead investigator Patricia Dietz said in a news release from the Center for the Advancement of Health.

"The percentage of SIDS deaths that might be avoided with smoking cessation is a significant number. For women who smoke and are considering pregnancy, we strongly recommend that they get preconception counseling for smoking cessation," Dr. Diane Ashton, deputy medical director of the March of Dimes, said in the news release.

The study appears online and in the July print issue of the American Journal of Preventive Medicine.

More information

The March of Dimes has more about smoking during pregnancy.