WEDNESDAY, June 22 (HealthDay News) -- Children born to mothers who smoked during pregnancy have lower levels of "good" HDL cholesterol, which may increase their risk of heart attack and stroke later in life, a new study suggests.

Australian researchers looked at 405 healthy 8-year-old children and found that those whose mothers smoked during pregnancy had HDL levels of about 1.3 millimoles per liter (mmol/L), compared to a normal level of 1.5 mmol/L in children whose mothers didn't smoke.

It's not known how smoking during pregnancy lowers HDL levels in children.

The study was published June 21 online in the European Heart Journal.

"Our results suggest that maternal smoking 'imprints' an unhealthy set of characteristics on children while they are developing in the womb, which may well predispose them to later heart attack and stroke. This imprinting seems to last for at least eight years and probably a lot longer," study leader David Celermajer, a professor of cardiology at the University of Sydney, said in a journal news release.

He and his colleagues noted that rates of smoking by pregnant women are still high -- about 15 percent in most Western nations. This means their findings could prove important in efforts to prevent heart disease.

"Children born to mothers who have smoked during pregnancy will need to be watched particularly carefully for other coronary risk factors," such as smoking, high blood pressure and high levels of "bad" low-density lipoprotein (LDL) cholesterol, Celermajer said.

More information

The U.S. Centers for Disease Control and Prevention has more about smoking and pregnancy.