Single mothers worse off than single fathers: Study

The income of single fathers, on the other hand, remains the same or increases with each added child in their family, the findings showed.

"Single mothers earn about two-thirds of what single fathers earn," said Karen Kramer, assistant professor of family studies at University of Illinois in Chicago, US.

In 2012, 28 percent of all US children lived with one parent. Of that number, 4.24 million single mothers lived below the poverty line compared to 404,000 single fathers, she noted.

The single most important factor that allows single-parent families to get out of poverty is working full-time, she said. "Single fathers are more likely to become single parents as the result of a divorce; single mothers are more likely never to have been married," Kramer added.