Women who smoke during pregnancy are 50 to 78 percent more likely than nonsmokers to give birth to babies with cleft lips or palates, say University of Michigan Health System researchers.
Cleft lip and palate are the fourth most common congenital birth defect and affect about one in 700 newborns.
In the February issue of Plastic and Reconstructive Surgery, researchers report that the risk of these birth defects rises with the number of cigarettes a pregnant woman smokes each day, after factors such as the mother’s age, race and educational level are considered.
Kevin Chung, M.D., M.S., and colleagues collected and analyzed data from the 1996 U.S. Natality Database, which is compiled by the Centers for Disease Control and Prevention’s National Center for Health Statistics. It includes information on each baby, as well as on each mother’s education, lifestyle and medical history.
The 1996 data included almost 4 million live births in all 50 states and information on smoking in 46 states. Of the births in states with smoking data, 2,207 babies were recorded as having cleft lips, palates or both. Researchers randomly selected 4,414 babies born without birth defects and compared the smoking habits of the mothers in both groups.
They found that mothers who smoked 10 or fewer cigarettes a day increased the risk of their babies’ developing cleft lip or palate by 50 percent. Those who smoked 11 to 20 cigarettes a day increased the risk by 55 percent, and mothers who smoked more than one pack per day raised the risk by 78 percent.
Researchers also found that mothers whose babies had cleft lip or palate were 37 percent more likely to smoke than those whose babies had other birth defects.
"More than 13 percent of the 3.9 million women in this study said they smoked, which is troubling by itself," said Dr. Chung, "but this new evidence makes it even more so."
Researchers say their findings reinforce the importance of educating women to not smoke while they are pregnant.
