About 40 percent of babies born in the United States were born to mothers who were not married, in 2015 according to the United Nations.
The statistic comes from the UN Population Fund's annual report, which notes that the rate has steadily increased since 1970, when only 10 percent of children were not born to married parents.
The trend is consistent with many Western countries — 60 percent of children were born to unmarried parents in the European Union in 2015, an increase from just under 20 percent in1970.
The UN notes that while mothers may not waiting for marriage to have children, it's likely that the children are still growing up with two parents. The study notes that in 2010, 1 in 10 European children lived with a single mother, while 1 in 4 in children lived with an unmarried couple.
The study also notes that mothers in the United States are waiting longer to have children. According to the UN, the average age of a woman when she gives birth to her first child has risen from about 22 years old in 1970 to about 26 years old in 2014.
The study suggests that educated women in developed countries are entering the workforce, but may choose to wait to start a family due to the lack of affordable health care, lack of parental leave or flexible schedules.
Read the entire UN study in the window below.
Alex Hider is a writer for the E.W. Scripps National Desk. Follow him on Twitter @alexhider.