Nicotine patches may be a healthier option for pregnant women who smoke, say medical researchers in Alberta who are studying the alternative.

Smoking cigarettes while pregnant increases both the risk of delivering a low birth weight baby, and the risk of health problems for the infant.

Previous studies on pregnant rats used too much nicotine, said Dr. Shabih Hasan, a professor in pediatrics at the University of Calgary who is investigating nicotine replacement therapy.

Some studies used the equivalent of 500 cigarettes a day, Hasan said.

Hasan and his colleagues in Calgary and Manitoba more accurately tested the amount of nicotine a pregnant women would use. Their study appears in this week's issue of Toxicology and Applied Pharmacology.

"It did not have any effect on the weight gain of the mother or how she was eating, or the baby's weight gain or growth," said Hasan. "It shows us there are constituents other than nicotine that would lead to the weight decrease in the babies."

Nicotine patches could be an alternative for women who won't give up smoking during pregnancy. Cigarettes contain thousands of chemicals and additives.

"Our current study has major implications for translational research in developmental toxicology and pharmacotherapy using nicotine replacement treatment as an aid to cessation of cigarette smoking in pregnant mothers," the researchers wrote.

So far, Hasan's research has used animals. The next step is to test patches on pregnant women who smoke.