Correction: A previous version of this post misspelled the name of Gloria Steinem.

Sandra Fluke, a third-year law student at Georgetown University and former president of the Students for Reproductive Justice group there, testifies during a hearing before the House committee in February. Fluke was blocked from testifying at an earlier House Oversight and Government Reform Committee's contraceptives hearing. (Alex Wong/GETTY IMAGES)

Men have long been the predominant sources for the news media on issues such as the economy, politics and the military. And a new analysis of campaign coverage found that women aren’t even the principal news source on a topic they would presumably know best: women’s issues.

Major news outlets, print and TV, turn mainly to male sources for their take on abortion, birth control and Planned Parenthood, according to a study by 4th Estate, a research group that monitors campaign coverage.

Women don’t even rate as the most common sources for reports about “women’s rights,” a catch-all category that excludes reproductive issues, the group said. Women accounted for less than a third, or 31 percent, of the sources in these reports, with men in the majority, 52 percent, and institutions and organizations comprising the balance.

On some topics, such as abortion, men were four to seven times more likely as women to be the ones offering an opinion, according to 4th Estate, an offshoot of Global News Intelligence, a company that monitors media sources for government agencies and companies. It concluded: “The gender gap undermines the media’s credibility.”

Michael Howe, a spokesman for 4th Estate, said his group’s findings suggest that reporters might have “an unconscious bias” when it comes to selecting people who offer expertise and opinions about the news. “The thinking [among reporters] may be that men have more authority on a topic than women do,” he said.

(Yes, I — a man — consulted another man for his opinion on why women’s views aren’t sought out by media types on women’s issues).

Women’s groups said the study reflects the under-representation of women in the media and among the elites whose views are most often sought by journalists.

“There’s been an ongoing complaint among women leaders that women’s voices simply are not there,” said Terry O’Neill, president of the National Organization for Women. “When Congress is only 17 percent female, when women are 3 percent of the CEOs and only 15 percent of [top corporate executives], you don’t have critical mass. What happens is that women aren’t there. We’re not noticed.”

The 4th Estate study analyzed about 50,000 quotes from 35 print sources, such as The Washington Post, the New York Times and USA Today, and the transcripts of 11 network news programs over the past six months. Excluding statements from the candidates themselves, it found that men accounted for roughly two-thirds of those quoted in newspaper articles, and made about 75 percent of the statements on such shows as MSNBC’s “Hardball,” Fox News’s “Special Report” and “Face the Nation” on CBS.

The study covered the period from November to April, which was an unusually active time for news about women’s issues. Topics included the controversy over the Susan G. Komen organization’s decision to stop and restart funding for Planned Parenthood; radio host Rush Limbaugh’s disparaging comments about contraception advocate Sandra Fluke; and conservative initiatives that Democrats have framed as a “war on women.”

O’Neill said “media decision-makers” bear some responsibility for the gender diversity in the nation’s newsrooms. “Frankly, there’s no excuse for [news staffs] not to be half women and half men,” she said.

Women were 40 percent of TV news staffs and 22 percent of radio news staffs last year, according to the Radio-Television Digital News Association. For daily newspapers, the figure was 37 percent in 2011, the American Society of News Editors found in its annual survey. However, men overwhelmingly occupy the most senior positions in news organizations.

Still, Julie Burton, president of the Women’s Media Center — which was founded by activist Gloria Steinem, actor Jane Fonda and writer Robin Morgan — said 4th Estate’s research confirms her organization’s findings that women’s “views and voices” are missing in print, television, radio, online and in film. It “underscores the critical need to hold media accountable for an equal voice and equal representation. The problem is that the public hears only half of the story,” she said.