A Gallup poll of Americans’ views on abortion again reports that slightly more Americans self-identify as pro-life instead of pro-choice. While the number of pro-life Democrats is down, a shift is apparent among Republicans and Independents.

A poll conducted May 3-6 showed 47 percent of Americans say they are pro-life while 45 percent say they are pro-choice, Gallup reports, claiming a margin of error of plus or minus four percentage points.

Particularly large increases in pro-life sympathies are apparent among young adults and those aged 50 to 64 years.

In 2009, 56 percent of Gallup respondents said abortion was morally wrong, a number which declined to 50 percent this year. Gallup said in light of this fact it was “not entirely clear” why Americans are more likely to embrace the pro-life view.

Since 2003, Republicans have been more likely to call themselves pro-life, as 68 percent now do so. Republican-leaning independents have been trending pro-life since 2005 and 61 percent say they self-identify as such now. Independents without a party preference became more likely to call themselves pro-life between 2003 and 2006 but have since held steady.

Self-identified pro-life Democrats have declined in number from 37 percent in 2003 to 31 percent in 2010. There was no movement among independents who lean Democratic.

Gallup suggested that without evidence showing Americans are growing more wary about the morality of abortion, “increased political polarization” may be a factor in Republicans’ preference for the pro-life label.

“Whatever the cause, the effect is that the pro-life label has become increasingly dominant among Republicans and to a lesser degree among independents, while the pro-choice label has become more dominant among Democrats,” its analysis concluded.