UNITED NATIONS — Twenty years after a landmark United Nations summit meeting in Cairo called on countries around the world to allow women greater control over their health and destiny, women worldwide have fewer children, are less likely to die of childbirth and have made great strides in literacy, according to a major report released Wednesday by the world body.

But a closer look at the report’s numbers reveals marked disparities. For instance, in the poorest communities, “women’s status, maternal death, child marriage” and other indicators of women’s well-being have “seen little progress in the last 20 years,” the report concludes.

In poor countries, for instance, pregnancy and childbirth are the leading cause of death among young women ages 15 to 19. Women continue to be paid less and they are more likely to work in jobs that are “less secure and with fewer benefits,” according to the report, by the United Nations Population Fund.

“Men have to change,” Babatunde Osotimehin, the fund’s executive director, told reporters here. “They have to accept gender equality.”

One study, cited by Mr. Osotimehin of Nigeria, said that worldwide, one in three women reported being physically or sexually abused.

In Asia, a separate study last year found that nearly half of the 10,000 men interviewed reported using physical and or sexual violence against a female partner, while a fourth of them said they had raped a woman or girl, with the vast majority saying they faced no prosecution. It cited another survey in the Democratic Republic of Congo, where one in three men reported having engaged in sexual violence.

The gains were most striking in education. In a majority of countries, there was gender parity in primary education, though there were abiding gaps in secondary schools and college. Maternal mortality fell by 47 percent over the last 20 years, though, the report pointed out, 800 women continue to die every day while giving birth. Global fertility rates fell by 23 percent between 1990 and 2010, reflecting rising education, life expectancy and access to contraception.

The report concluded: “Progress has been unequal and fragmented.”

The changes have come at a time when the world has prospered over all, though women in the poorest countries, along with poor women in some richer countries, have not seen their lives improve, the report said.

“In conditions of structural poverty,” the report said, “the threats to women’s survival are especially acute, due to the lack of access to health services, particularly sexual and reproductive health services, and the extreme physical burdens of food production, water supply and unpaid labor that fall disproportionately on poor women.”

The report repeatedly cites growing economic inequality worldwide, pointing to a recent Credit Suisse study that shows that fewer than 1 percent of adults worldwide control 41 percent of the wealth, while more than two-thirds of the world’s adults control only 3 percent of the wealth.

The report also documents a marked demographic tilt, with much of the industrialized world inexorably aging and the world’s youth concentrated in the developing world. Indeed, 90 percent of people between the ages of 10 and 24 live in the developing world.

Despite plummeting fertility rates and the graying of Europe and East Asia, there has never been a larger generation of young people. That age group accounted for 28 percent of the global population in 2010 — and higher in South Asia and Africa.

The needs of these young people, the report emphasized, will have to be central to any development agenda, and not just because of their sheer numbers. They will have to be self-sufficient because they are likely to have fewer children to later support them and because most of them are in poor countries where education and health are in dire shape and there are a dearth of what the report calls “good jobs.”

Those countries — like India and Nigeria — that have a high proportion of young people and declining fertility levels can take advantage of that “temporary demographic bonus,” the report says, but only if it can educate its youth and offer access to work.