URBANA, Ill. – Single mothers earn significantly less than single fathers, and they’re penalized for each additional child they have even though the income of single fathers remains the same or increases with each added child in their family. Men also make more for every additional year they invest in education, further widening the gender gap, reports a University of Illinois study.

“Single mothers earn about two-thirds of what single fathers earn. Even when we control for such variables as occupation, numbers of hours worked, education, and social capital, the income gap does not decrease by much. Single mothers are far more likely to live in poverty than single fathers, and they do not catch up over time,” said Karen Kramer, a U of I assistant professor of family studies.

In 2012, 28 percent of all U.S. 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. “A 2011 study shows that in single-parent families below the poverty line at the end, only 15.1 percent were employed full-time year-round.”

Previous studies show that 39 percent of working single mothers report receiving unearned income, assumed to be child support. That means fathers are contributing only 28 percent of child-rearing costs in single-mother households, she said.

The pathway into single-parent households differs by gender, 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,” she explained.

“Divorced single parents tend to be better off financially and are more educated than their never-married counterparts. The most common living arrangement for children after a divorce is for mothers to have custody. Single fathers with custody are more likely to have a cohabiting partner than single mothers, and that partner is probably at least sharing household tasks. Single mothers are more likely to be doing everything on their own,” she said.

Often single mothers have both the stress of raising children alone and crippling financial stress, she added.

Society still stigmatizes single mothers, she noted. “People think: How did you get in this position? It’s irresponsible to be a single mother with so many kids. Now you don’t have time to work.”

She pointed out that the role of women as caretakers saturates every aspect of our culture. “Women perform most caregiving work for children, elders, and dependent persons, both within their own families and as paid employees,” she said.

“We need to encourage women to invest in education. And, as policymakers, we need to make sure that women and men get the same return on that investment,” she said.

Kramer recommended that more emphasis and pressure should be placed on fathers and their ability to pay child support and spousal maintenance; raising the minimum wage to a living wage; and providing similar benefits and rewards for part-time work as the ones full-time workers get.

Affordable housing in a safe neighborhood, access to public transportation, food support, child care and health care for single mothers should also be supported, she added.

Kramer noted that single mothers who don’t participate in Social Security because they are not working are setting themselves up for lifelong poverty.

“Social Security is designed to protect those who have lengthy work histories or women who get married. Single motherhood presents a continuing crisis that requires efforts to end women’s poverty by enforcing anti-discrimination laws and offering opportunities and training for better-paying positions,” Kramer said.

“Comparison of Poverty and Income Disparity of Single Mothers and Fathers Across Three Decades, 1990-2010” appears in a recent issue of Gender Issues. Co-authors are Karen Z. Kramer of the University of Illinois, Laurelle L. Myhra of the Native American Community Clinic in Minneapolis, and Virginia S. Zuiker and Jean W. Bauer of the University of Minnesota. Funding was supplied by USDA.