Jun 17, 2014 07:33 AM EDT By Staff Reporter, UniversityHerald Reporter

A latest John Hopkins University study found that less-educated adults, who are almost 30 years old, do not wait until marriage to have kids. Researchers said that it is now an "unusual" trend for non-college graduates to have all their children within marriage.

"Clearly the role of marriage in fertility and family formation is now modest in early adulthood and the lofty place that marriage once held among the markers of adulthood is in serious question," sociologist Andrew J. Cherlin said in a press release.

Cherlin said that the value of marriage is most likely upheld by college graduates because most of them think about having a family only after getting married.

For the study, researchers analysed data from the National Longitudinal Survey of Youth studying samples of 9,000 "early adults" who were between 26 and 31 years in 2011.

The researchers found that 81 percent of births reported by women and 87 percent of births reported by men had occurred to non-college graduates. Overall, 57 percent of births had occurred outside wedlock for both men and women. Plus, 64 percent of women and 63 percent of men had at least one child outside of marriage. It was 74 percent among women and 70 percent among men without 4-year college degrees.

"The literature on early adulthood often suggests that this period can be a valuable time of self-exploration free of adult responsibilities," said Cherlin, the Benjamin H. Griswold Professor of Public Policy at Johns Hopkins. "But this characterization would seem to better apply to well-educated middle-class early adults with their typically long period of college attendance, perhaps followed by graduate school, and their postponement of childbearing until after marriage."

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