The study, published in Alcoholism: Clinical and Experimental Research, found most of those women were uninformed about the risks to their babies' health.

"Our results surprised us because we didn't think that the women were so massively going to answer that they were so ignorant of the dangers of alcohol during pregnancy," study leader Ingrid de Chazeron of the Centre Hospitalier Universitaire in Clermont-Ferrand, France, said in a statement. De Chazeron said the percentage of U.S. moms-to-be having a drink a day is much less -- about 12 percent.

The study data -- compiled from 837 pregnant women surveyed at public and private obstetric centers from July 2003 to June 2004 -- showed 13.7 percent of the participants said they had at least one binge-drinking episode in which they had five or more drinks.

Alcohol can cross the placental barrier and lead to fetal alcohol syndrome -- central nervous system or other damage resulting in physical, mental or behavioral problems. Two of the women in the study gave birth to babies with fetal alcohol syndrome.