Research released last week by the U.S. Census Bureau's American Community Survey says states with a higher percentage of out-of-wedlock births in 2011 tended to have a higher incidence of poverty.

The American Community Survey found that 36 percent of the 4.1 million women who gave birth in the U.S. that year were unmarried, up from 31 percent in 2005.

Utah had the nation's lowest out-of-wedlock birth rate in 2011, at 14.7 percent, followed by New Hampshire at 20 percent. The District of Columbia had the highest rate, at 50.8 percent, followed closely by Louisiana at 48.7 percent, Mississippi at 48.1 percent and New Mexico at 47.6 percent.

"The increased share of unmarried recent mothers is one measure of the nation's changing family structure," report co-author Rose Kreider said. "Non-marital fertility has been climbing steadily since the 1940s and has risen even more markedly in recent years."

There was a .6 Pearson's correlation between state-level poverty and the percentage of women reporting out-wedlock births, according to the report. A correlation of 0 would suggest no relationship between the two, while correlation values of 1 or -1 would suggest a strong correlation.

Coupling statistics for the percentage of women without a high school degree in a state and the state's median income "explains about 67 percent" of out-of-wedlock births, according to the report. The precise correlation between solely educational attainment and out-of-wedlock births was not included in the report.

By educational attainment, 57 percent of women without a high school degree were unmarried when they gave birth, compared to 8.8 percent of women with a bachelor's degree or more. The percentages for women with just a high school degree and some college fell between the two.

Nationwide, African-American women reported the highest rate of out-of-wedlock births, at 67.8 percent. American Indian or Alaska Native women reported a 64 percent rate, while Hispanics reported 43 percent and non-Hispanic whites reported 26 percent. Asian-Americans reported the lowest rate of out-of-wedlock births, at 11.3 percent.

Data revealed a significant link between income and out-of-wedlock births. Of women making less than $10,000 who gave birth in the previous year, 68.9 percent were not married. That statistic dropped progressively going up the household income ladder, with a 9 percent rate for households earning more than $200,000 a year.

Younger women who gave birth were also more likely not to be married. Of new mothers between the ages of 15 and 19, 86.1 percent were unmarried, compared to 61.5 percent of women ages 20 to 24 and 31.9 percent of women ages 25 to 29. The percentage dipped into the teens for women in their 30s and was slightly higher for older women.

The report pulls from the Census Bureau's poverty count, which may overestimate the poverty rate by overlooking cohabiting couples. According to last week's report, up to 40 percent of all children will live in a cohabiting household by age 12. A 1998 study by the University of Michigan - which is posted on the Census Bureau's website - calculated a possible four percent overestimate of the national poverty rate in the 1990 Census by not treating cohabitators who pool resources as family units.