Single-parent families are about four times as likely as married-couple families to be in poverty, according to new US figures.

A study produced by think tank Child Trends showed that 37.2pc of single parent families were in poverty, while only 8.8pc of married families were in poverty.

This difference has important implications, given that the proportion of families headed by single mothers has followed an upward trend across the past decade.

The study, Two Generations in Poverty: Status and Trends among Parents and Children in the United States, 2000-2010 also found that children growing up in single-mother households (at 46.9pc) experience far higher rates of poverty than those growing up in married couple households (at 11.6pc).

According to the figures, family structure is strongly related to poverty status and low-income status, with single-parent families—and those families headed by single mothers in particular—having higher levels of poverty than married-couple families.

Even where at least one member of the household is working fulltime and all year round, families headed by a single parent are still more likely to be poor than families headed by married couples, the study showed.

For example, in 2010, the poverty rate (at 13 percent) for single-mother families with at least one member of the family working full-time and year-round was more than three times higher than the rate (at 3.9 percent) for married-couple families with at least one family member working full-time and year-round.

Families headed by young householders ages 18-24 are more likely to be poor or low income than families headed by householders ages 25 to 54.

Between 2009 and 2010, poverty rates for family households increased across different types of families. In 2010, 37.2 percent of single-parent families were living in poverty, up from 35.2 percent in 2009. In 2010, 8.8 percent of married-couple households were in poverty, up from 8.3 percent in 2009.

In 2010, approximately 43 percent of children were low-income. Mirroring recent trends in child poverty, the percentage of children who are low-income increased since the recession hit in 2007, after remaining stable throughout much of the decade.

More than one in five children in the United States lived in poverty in 2010, with one in ten living in deep or extreme poverty.

In 2010, the percentage of children living in poverty reached nearly 22 percent, up from 15.6 percent in 2000

The percentage of children living in poverty remained relatively stable during the first half of the decade, but has increased each year since 2006.

The figures were drawn from data from the US 2010 Census.

The data is based on the official US poverty measure, which varies by family size and composition, and is updated annually to reflect inflation as measured by the Consumer Price Index.
 
In 2010, for instance, the poverty threshold for a family of four with two related children under 18 years was $22,113.
 
People living in households with incomes below 200 percent of the official poverty line are considered to be low-income, while those with incomes below 50 percent of the federal poverty line are living in deep or extreme poverty.
 
In October 2011, the Census also published preliminary poverty estimates based on the Supplemental Poverty Measure, which is being developed and refined based on recommendations from an interagency technical working group with representatives from the U.S. Census Bureau, the Bureau of Labor Statistics and other federal agencies.
 
This uses poverty thresholds that are based on the Consumer Expenditure Survey data and that are adjusted to account for in-kind benefits, as well as taxes, work and out-of-pocket medical expenses, the cost of basic living expenses, such as housing and food.

The number and percent of people living in poverty vary across the two measures. For instance, in 2010, 15.1 percent of all people and 21.0 percent of children in the U.S. were living below poverty using the official poverty measure.
 
By comparison, 16 percent of all people and 18.2 percent of all children were living below poverty using the Supplemental Poverty Measure.

In addition to the Supplemental Poverty Measure, over the past several years, the Census has released poverty estimates for alternative or experimental poverty measures that were developed based on recommendations from a 1995 National Academy of Sciences (NAS) report, Measuring Poverty: A New Approach.
 
In 2010, the official poverty measure produced estimates that fell in the middle range of the eight poverty estimates produced using the NAS based measures. However, earlier in the decade, the poverty estimates based on the official poverty measure tended to be lower than those produced using the NAS based estimates.