More women worldwide are smoking during pregnancy, and secondhand-smoke exposure also is a growing problem, according to researchers at RTI International.

A survey of 8,000 pregnant women in developing nations in Latin America, Africa and Asia found that about 18 percent smoked during pregnancy, up to one-third used smokeless tobacco, and about half were exposed to secondhand smoke.

"This study indicates that public health officials in developing nations should take immediate steps to prevent and reduce tobacco use and secondhand smoke exposure among pregnant women," said Duane Alexander, M.D., director of the National Institute of Child Health and Human Development (NICHD).

"Where tobacco use rates are still low, we have the opportunity to avert an increase in tobacco use among women, especially pregnant women, in the developing world," added Linda Wright, M.D., scientific director of the Global Network, in NICHD's Center for Research for Mothers and Children.

The study appears in the April 2008 issue of the American Journal of Public Health.