A narrow majority of Americans now consider abortion "morally unacceptable," while less than 10% disapprove of birth control, a new Gallup Poll has found.

Fifty percent of the survey respondents disapproved of abortion, with 42% approving, though the poll has a margin of error of four percentage points. A year ago, Gallup found that an equal split among Americans- 48% each- identified as "pro-life" and "pro-choice."

The survey, released late last month, tracks changes in public attitude over time toward a range of social and moral issues. The latest figures are from May 2019 and are based on telephone interviews with a random sample of just over 1,000 U.S. adults.

The highest proportion of disapproval for abortion that Gallup has measured is 56%, recorded in 2009. That year just 36% of respondents considered abortion morally acceptable.

At the same time, however, approval of sexual relations between an unmarried man and woman edged up two points since last year to 71%, which is the highest approval rating Gallup has yet recorded on that issue. Approval for divorce is also at an all-time high, at 77%.

Ninety-two percent said they found the use of artificial birth control morally acceptable, which was the highest approval margin of any of the social issues proposed in the survey. Having a baby outside of marriage has also edged upwards in moral acceptability over the years since 2002.

Another notable topic was pornography- 61% of respondents consider it morally unacceptable. Pornography hit a "high point in moral acceptability" last year, but this year has settled back into previous trends, Gallup reports.

Sixty-four percent approved of embryonic stem cell research, and a similar percentage approved of gay or lesbian relations. Just over half voiced approval for physician-assisted suicide, and 60% approved of the death penalty.  

The least acceptable scenario for the respondents, with nearly 90% disapproving, was "married men and women having an affair." Human cloning wasn't far behind, with 85% disapproval, followed by suicide at 79%.

The study differentiated between respondents who identified as "conservative" and "liberal"; according to the poll, just 23% of conservatives versus 73% of liberals consider abortion morally acceptable, a 50% difference.

Notably, the liberal/conservative divide was virtually nonexistent when it came to birth control, with 93 and 90% approving, respectively.

Gallup released another survey last month that found that among respondents who identify as pro-life, 71% support exceptions under the law for cases where the mother's life is in danger, and 57% for cases of rape and incest.