Children of women with less than a high school education are more likely to have received timely childhood vaccinations than the children of college graduates, according to a new study.

The paper, published online Dec. 28, will appear in the February issue of The American Journal of Public Health. Scientists studied data on 11,860 families from the National Immunization Survey, a nationwide survey of vaccination among children 19 to 35 months old that includes information on race, ethnicity and socioeconomic status.

Children of mothers who had not completed high school were 16 percent more likely to have up-to-date vaccinations than children of college graduates. While black children were 11 percent less likely to be up to date than white children, Hispanic children were 11 percent more likely. The poorest children, without considering race or ethnicity, were just as likely as the richest to have completed their vaccination schedule.

"The way the health care system is organized for immunization services may account for the variations," said Jennie J. Kronenfeld, the senior author of the study. "Or cultural differences may overcome the barriers to immunization that they don't in other kinds of health care."

Dr. Kronenfeld, a professor of sociology in the School of Social and Family Dynamics at Arizona State University, offered a possible explanation for the difference between the children of college graduates and those of mothers who had not graduated from high school. "There is a controversy among more educated mothers about the safety of certain kinds of immunization," she said. "That may be part of what is going on here, but we don't know for sure."