It's not difficult to view abortion as a contentious issue. With equal percentages of Americans -- 48% each -- identifying themselves as "pro-choice" and "pro-life" in Gallup's May 2018 update on abortion, the country looks to be completely polarized on the matter.

The two sides also diverge when it comes to the legality of first-trimester abortions. Nine in 10 pro-choice Americans say abortion should generally be legal in the first three months of pregnancy, while six in 10 pro-life Americans believe it should be illegal.

Support for First-Trimester Abortions, by Self-Identified Position on Abortion Do you think abortion should generally be legal or generally illegal during each of the following stages of pregnancy? How about in the first three months of pregnancy? U.S. adults Pro-choice Pro-life % % % Legal 60 90 33 Illegal 34 8 60 Depends/Unsure 5 2 8 Gallup, May 1-10, 2018

At the same time, there are two important areas of consensus that have typically been respected in U.S. abortion laws. One involves protecting abortion rights when pregnancy endangers a woman's life. The other is keeping abortion legal when pregnancy is caused by rape or incest.

According to Gallup's 2018 abortion survey, not only do most Americans as a whole favor these protections, but so do majorities of pro-life Americans -- 71% for the endangered woman's life exception and 57% for cases of rape or incest. Support for these allowances is nearly universal among pro-choice Americans.

Percentage Saying Abortion Should Generally Be Legal in Each Situation U.S. adults Pro-choice Pro-life Abortion group gap % % % pct. pts. Woman's life would be endangered 83 93 71 +22 Pregnancy the result of rape or incest 77 96 57 +39 Child would be born with life-threatening illness 67 93 39 +54 Child would be born mentally disabled 56 85 25 +60 Child would be born with Down syndrome 49 79 18 +61 Woman doesn't want child for any reason 45 77 11 +66 Gallup, May 1-10, 2018

The general agreement seen on woman's life and rape/incest protections contrasts with a much thornier picture relative to the laws on abortion in cases when the child would be physically or mentally disabled or at the woman's discretion. These spark much stronger differences between pro-choice and pro-life Americans, and are usually where conflict erupts in the debate.

Americans' Views on Abortion Are Complex, yet Clear

Somewhere between NARAL Pro-Choice America and National Right to Life lies a nuanced view of abortion, which is where the largest segment of Americans reside. Fifty percent of Americans in Gallup's May 2018 update on abortion views said abortion should be "legal only under certain circumstances." The rest were divided between those saying it should be legal in all cases (29%) and those in favor of it being illegal in all cases (18%).

Even with this question, shades of gray tend to blur the bright lines separating so-called partisans on abortion. Barely half of pro-choice Americans think abortion should be legal in all cases, while four in 10 favor it in only certain circumstances. Only a third of pro-life Americans think abortion should be illegal in all cases, while the majority take the middle position.

U.S. Views on Legality of Abortion Do you think abortions should be legal under any circumstances, legal only under certain circumstances or illegal in all circumstances? U.S. adults Pro-choice Pro-life % % % Legal under any circumstances 29 54 7 Legal only under certain circumstances 50 41 59 Illegal in all circumstances 18 3 33 Gallup, May 1-10, 2018

The anti-abortion bill recently passed in the Alabama Senate and awaiting Gov. Kay Ivey's signature would outlaw all abortions at all stages of pregnancy, except those determined necessary to save the life of the mother. That may technically fit within the "only under certain circumstances" framework that 50% of Americans and 59% of pro-life Americans say they support. However, by excluding a provision that would also allow pregnancies caused by rape or incest to be terminated, the Alabama bill falls outside the views of most Americans.

The bill is reportedly designed to directly challenge Roe v. Wade, but it may also test the bounds of public tolerance for abortion laws that don't exactly square with Americans' own beliefs.

A more detailed review of national views on the legality of abortion in each trimester appears in this 2018 article, and for Gallup's full analysis of public opinion on abortion, visit the Abortion topic page.