Infants are more than 10 times as likely to die in the District’s poorest ward than they are in its richest, the international advocacy group Save the Children said Monday.

The findings, released Monday night as part of the group’s annual State of the World’s Mothers report, underscore how vast income inequality in the capital of the world’s richest country continues to yield startling disparities in health and survival at the neighborhood level.

The 80-page global health report, which offered comparative figures for major international metropolitan areas, also ranked Washington last on a list of 25 wealthy capital cities, including Athens and Madrid, which have struggled against economic crises, as well as the capital of a former Soviet republic.

The most recent ward-by-ward data available for Washington dates to 2012, when the city’s average death rate for infants was 7.9 per 1,000 live births, higher than the national average of 6.1. (A number of other American cities, such as Cleveland and Detroit, have far higher rates than the District.)

Last year, then-Mayor Vincent C. Gray released preliminary data for 2013, showing a significant drop in infant deaths to 6.6 per 1,000 live births, an all-time low for the city. In 1999, the rate was 15.)

Gray (D) also announced a five-year public-private partnership, in coordination with the Clinton Global Initiative, to further reduce infant mortality in the District.

But recent ward-by-ward statistics are still forthcoming, and Save the Children has cautioned that “declining city averages often mask or hide huge gaps in mortality rates among rich and poor children.”

According to the 2012 figures, the infant death rate in Ward 8 was 14.9 per 1,000 live births — on par with the capitals of El Salvador and Cambodia — while the rate in Ward 3 was 1.2, a figure on par with the lowest infant mortality rates worldwide seen in cities such as Tokyo and Stockholm.

Roughly twice as many babies are born each year in Ward 8 as in Ward 3. But while one infant died in Ward 3 over the course of a two-year period in 2011 and 2012, 24 babies died in Ward 8. Most of the deaths were the result of premature births.

“I think it’s primarily due to what we call the ‘toxic stressors’ and the social determinants of health,” said Marcee White, director of the Children’s Health Center at THEARC: Children’s Health Project of D.C., a clinic in Ward 8. “Most of the community in Ward 8, they experience these toxic stressors and they really don’t have the buffers” that the District’s wealthier residents have, White added.

“The Bowser Administration is committed to looking at innovative solutions to address health disparities that exist in the District,” Mike Czin, a spokesman for D.C. Mayor Muriel E Bowser (D), said in an e-mailed statement. “The District recently established the Office of Health Equity that is looking at outcomes and upstream issues that are really the root causes of health disparities. We will continue to leverage resources to improve outcomes for infants and residents of all ages.”

The District has also received tens of millions of dollars during the past two decades from the federal Healthy Start program. But last September, the program said the District had not qualified for a $4 million grant, threatening the continuity of certain health programs geared toward at-risk mothers and children.

Roughly half of all children in Ward 8 live in poverty, according to Save the Children. And a majority of households with children in the ward are headed by single mothers, who are often struggling against the additional stresses of holding a job, feeding their families and paying the bills, White said.

“It’s my opinion that the women in Ward 8 are delivering their young premature due to the stresses that they experience while they are carrying their child,” said White, who is a pediatrician.

Parents struggling to meet income needs also struggle to maintain a healthy diet and are less knowledgeable about child health, White said. Grocery stores are more scant in Southeast Washington. And working hours present obstacles to medical checkups.

White said 15 percent of her clinic’s business occurs during special extended hours, offered from 5 to 8 p.m. three nights a week, and for a half-day Saturday. Most Ward 8 families head to the emergency room “as their usual source of care,” she said.

After prematurity, another prominent cause of infant death in the ward is attributable to sudden infant death syndrome. The syndrome, which results in the unexplained death of an otherwise healthy baby, usually occurs during sleep and can reflect a lack of education about healthy sleeping conditions for infants.