More and more young women are walking with baby strollers before they walk down the aisle. A new study from the CDC’s National Center for Health Statistics finds the percentage of babies born to unmarried mothers has risen dramatically within the past few decades.

Birth rates among unmarried U.S. mothers are highest for women in their early 20s. In fact, unmarried mothers accounted for six out of every ten births among women in that age range in 2007. The study also finds that between 1980 and 2008 the proportion of birth to unmarried women in the U.S. more than doubled from 18% to 40%.