An anti-abortion group says the numbers reflect a "pro-life shift," while others argued it may mean decreased access to abortion.
But the federal researchers who released the new numbers said Monday they don't know if the new numbers mean attitudes about abortion are changing.
"People have all kinds of attitudes that don't always reflect what they choose to do," said Anjani Chandra of the National Center for Health Statistics.
U.S. women of childbearing age who were surveyed in 2002 revealed that 14 percent of their recent births were unwanted at the time of conception, the researchers said.
In a similar 1995 survey, only 9 percent were unwanted at the time of conception.
The latest findings are consistent with the falling rate of abortions, according to the Guttmacher Institute, a New York-based nonprofit group that researches reproductive health issues.
In 1995, for every 100 pregnancies that ended in abortion or a birth, almost 26 ended in abortion. In 2002, 24 ended in abortion, according to Guttmacher data.
That information seems to be in sync with the federal data released Monday, said Lawrence Finer, Guttmacher's associate director for domestic research.
"The two statistics together suggest but don't confirm that a greater percentage of unintended pregnancies resulted in births rather than abortions," Finer said.
The Guttmacher Institute is nearly finished with a study of that question, but Finer declined to discuss the results before they have been published.
Others feel the link is clear-cut.
"I don't think there's any mystery here," said Susan Wills, of the U.S. Conference of Catholic Bishops.
The new data underscores that more women are turning away from abortions, even when it's a pregnancy they don't initially want, said Wills, associate director for education in the Conference's Secretariat for Pro-Life Activities.
"It shows a real pro-life shift," she said.
Erin Mutcheler, 24, thought about having an abortion after becoming pregnant but was persuaded not to by a friend who'd had an abortion and regretted it.
There also were family considerations her mother works for the U.S. Conference of Catholic Bishops. And, she said, her attitude about unwanted pregnancies had gradually changed.
Mutchler, of Glen Burnie, Md., had a girl last month and said she's delighted by her daughter, Kaylee. "I can't imagine not having her," she said.
Finer, though, suggested the shift may reflect not only a diminishing demand for abortions, but also a decline in abortion providers, Finer said.
The number of U.S. abortion providers fell steadily in the last decade, from 2,400 in 1992 to 1,800 in 2000. The reason is not clearly known, although increasing government restrictions of abortions have made it increasingly difficult to provide the procedure, Finer said.
Karen Pearl, interim president of the Planned Parenthood Federation of America, said she has detected no shift in general attitudes toward or away from abortion.
"I think this kind of statistic says more about access to family planning, medically accurate sex education and access to abortion than it does about societal values," she said.
The National Center for Health Statistics surveyed 7,643 U.S. women on that and many other family planning and reproductive health questions in 2002 and early 2003. The surveyed women were between the ages of 15 and 44. Researchers only recently completed their analysis of survey questions.
Among the questions: "Right before you became pregnant, did you yourself want to have a baby at any time in the future?"
If they said no, the pregnancy was defined as "unwanted." Pregnancies that occurred sooner than the woman wanted were instead classified as "mistimed," said Chandra, lead author of the federal study.
The proportion of unwanted births at time of conceptions was highest among girls under 18 25.4 percent. It was lowest among women 30 to 44 10.4 percent.
The proportion was higher for black women (26.2 percent) than for Hispanics (16.8 percent) and whites (10.7 percent).