Long gone are the days when it was frowned upon to have a child out of wedlock. Single women are smiling at the sight of their newborn babies, as more unwed women over the age of 35 are having children.

According to a report for the Centers for Disease Control and Prevention (CDC), the overall birth rates for unmarried women in the U.S. has dropped 14 percent in 2013, but the number of cohabiting births for middle-aged women has increased. 

The birthrate for middle-aged, unwed women ages 35 to 39 increased by 7 percent from 2007 to 2012. In the same time frame, unwed women ages 40 to 44 had a birthrate increase of 29 percent. Teenagers and black and Hispanic women saw a decrease in unmarried birthrates.

Author of the study and CDC statistician Sally Curtin links this increase to the fertility options available for older, single women. "There's more out there for women to meet their fertility goals," she said.

While the mothers are unwed, they are not alone. Analysis of federal data revealed that the number of nonmarital births within cohabiting relationships rose from 41 to 58 percent, based on data collected between 2002 and 2013.

"What's happened is the percent of nonmarital births within cohabiting unions has been increasing, but now it's increased to the point where the majority of nonmarital births are to women that are cohabiting," said Curtin. Currently, 40 percent of U.S. children are born to unwed mothers of all ages.

The study says that the increase of cohabiting births could be the result of increasing social and financial support from partners.