More than half of new D.C. mothers are unmarried, more than any state in the nation, according to census data released Wednesday.

Nearly 51 percent of women in the District between the ages of 15 and 50 who gave birth in the past year did so without being married, just beating out Louisiana at 49 percent and Mississippi and New Mexico at 48 percent. Utah, at 15 percent, had the lowest rate of unmarried mothers.

Nationally, nearly 36 percent of recent births were to unmarried mothers, up from 31 percent in 2005. D.C.'s figure, however, actually dropped from 53.3 percent in 2010.

Maryland checked in at almost 39 percent, up from 33.1 percent in 2010, while 31 percent of new mothers in Virginia were unmarried, inching down from 31.8 percent.

Baby blues
Total births Nonmarital births Percent nonmarital births
D.C. 7,070 3,591 50.8%
Maryland 78,351 30,221 38.6%
Virginia 110,163 34,591 31.4%
U.S. total 4,113,472 1,467,435 35.7%
Source: U.S. Census Bureau
Highest nonmarital birth rate, metropolitan areas
Flagstaff, Ariz. 74.6 percent
Greenville, N.C. 69.4 percent
Lima, Ohio 67.5 percent
Myrtle Beach, S.C. 67.4 percent
Danville, Va. 67.3 percent
Brunswick, Ga. 66.2 percent
Redding, Calif. 63.8 percent
Monroe, La. 62.5 percent
Sumter, S.C. 61.6 percent
Albany, Ga. 61.5 percent
Lowest nonmarital birth rate, metropolitan areas
Cheyenne, Wyo. 4.7 percent
Palm Coast, Fla. 6.2 percent
Jonesboro, Ariz. 8.0 percent
Provo, Utah 8.2 percent
Missoula, Mont. 8.6 percent
St. George, Utah 10.4 percent
Logan, Utah-Idaho 10.7 percent
Kennewick-Pasco-Richland, Wash. 12.2 percent
Bremerton, Wash. 12.5 percent
Lake Havasu City-Kingman, Ariz. 12.7 percent
Source: U.S. Census Bureau

"The increased share of unmarried recent mothers is one measure of the nation's changing family structure," said Rose Kreider, a family demographer with the U.S. Census Bureau. "Nonmarital fertility has been climbing steadily since the 1940s and has risen even more markedly in recent years."

High rates of unmarried mothers are correlated with high rates of poverty and low rates of education. Almost half of new mothers with only a high school education are unmarried, compared with less than 9 percent of those with a bachelor's degree or higher.

Race is a related factor -- 68 percent of black women who gave birth in the past year were unmarried, compared with 43 percent for Hispanic women, 26 percent for white women and 11 percent for Asian women, according to census data.

Native-born new mothers, at 39 percent, were more likely to be unmarried than immigrant mothers, at 24 percent.

While D.C.'s rate has actually fallen, the demographics of unmarried motherhood are shifting, according to Peter Tatian, a senior research associate at the Urban Institute. Even the District's gentrifiers may be having more children out of wedlock, he said.

"I think that there's this national trend that cuts across different income groups -- there are just more unmarried women who are having children," Tatian said. "Now it looks like it may be not so strongly associated only with poverty."

That doesn't mean poverty doesn't play a large role. Eighty-six percent of births in Southeast's Ward 7 were to unmarried mothers, compared with 5 percent in Ward 3 in the posh Northwest, Tatian said. Still, Wards 1 and 4, which have more income diversity, have rates of 49 percent and 54 percent, respectively.

"It used to be that we thought of out-of-wedlock birth as something that just happened to people in impoverished urban areas," said Isabel Sawhill, co-director of the Brookings Institution Center on Children and Families. "Unwed childbearing is now the norm for women under 30."

Sawhill chalked up the trend partly to changing attitudes to single motherhood along with poorer economic prospects for the men they would marry.

"Women are doing better than men these days educationally and often in terms of their job prospects," she said. "They may want to get married, but they don't need to for economic reasons."

Children raised by unmarried mothers can see adverse effects, however. A study by researchers at the University of Texas and Princeton University found that children born to unmarried parents often see those parents go through three or more partnership changes. Each change is associated with an increase in behavior problems.

"Those cohabitations are not terribly stable," Sawhill said. "It's not as good for kids as growing up in a two-parent family."