Most Americans remain opposed to overturning the controversial U.S. Supreme Court decision in Roe v. Wade, which 40 years ago legalized abortion at least in the first three months of pregnancy, according to a poll released Wednesday.

The Pew Research Center found that 63 percent of Americans said that Roe v. Wade should not be completely overturned, compared with 29 percent who said it should be. These opinions have changed little from surveys in 2003 and 1992, Pew reported.

Michael Dimock, director of the Pew Research Center for the People and the Press, said it is uncommon to see so little change in attitudes on a controversial issue.

“They really haven’t changed a lot over the years, which is kind of interesting, because a lot of other social issues have changed a lot — gay marriage being the most notable example,” he said.

He noted that opinions on such issues as same-sex marriage sometimes have a sharp generational divide, with younger people more likely to favor it, so national feelings change over time.

Elke and Don Hassenbein of Palmyra, Pa., hold signs during a pro-life demonstration Monday in downtown Lebanon, Pa. (Earl Brightbill/AP)

But the abortion issue shows only modest generational differences and no gender gap.

Those most likely to favor upholding Roe v. Wade, at 69 percent, are “baby boomers,” ages 50 to 64.

That group was followed by those who are 18 to 29 years old, who favored upholding the decision by 68 percent.

There are still wide religious differences over whether to overturn Roe v. Wade, which was decided on Jan. 22, 1973, and the morality of abortion, the poll found. White evangelical Protestants are the only religious group in which a majority (54 percent) favored overturning the decision.

Large percentages of white mainline Protestants (76 percent), black Protestants (65 percent) and white Catholics (63 percent) say the ruling should not be overturned.

The poll also found that 47 percent of Americans said they believe it is morally wrong to have an abortion. These opinions have changed modestly in recent years.

Younger people are less likely to know what Roe v. Wade was about. Although most respondents over 30 knew that it dealt with abortion, only 44 percent of those under 30 knew that.

The poll was based on interviews with a national sampling of 1,502 adults, 18 or over, and has a margin of error of plus or minus 2.9 percentage points.

— Reuters