At first, there is nothing out of the ordinary about Kristin Martin and her husband, Nate.

She’s 34, a college graduate who works as a sales manager at a Marriott hotel. He’s 35 and works as a software engineer. They met in college and they’ve been married for six years. They recently purchased their first home together in Morris Plains.

Swap out the details and the Martins’ lives would mirror tens of thousands across New Jersey. But Kristin and Nate actually represent a shift in what defines the New Jersey suburb as we know it, all because of one small detail — the Martins have no children.

An analysis of Census data by The Star-Ledger shows that for the first time the number of families in suburban and rural New Jersey without children has surpassed those with kids, a trend that has unfolded over the past several decades, and in doing so, fundamentally altered the demographic fabric of the state.

The reasons for this are twofold.

Baby Boomers, now approaching retirement age, have become empty nesters, as their children move out and look to begin their own families.

"In 2010, Baby Boomers really dominated the 50-something- year-old population," said James Hughes, dean of the Edward J. Bloustein School of Planning and Public Policy at Rutgers University. "This is a trend that’s been going on for a long time, and it’s something we’re going to continue to see over the next 20 years as more of this generation reaches retirement."

However, experts say it’s the evolution of the Baby Boomers’ children that is driving the other end of this trend — young couples are getting married later, and when they do are putting off having children.

"I don’t think I was really prepared for it. There was a lot of other stuff going on in our lives," said Kristin Martin, who is expecting her first child in March, about the thought of becoming a mother in her 20s.

Her husband, Nate, said while he and his wife had always wanted to have children, it didn’t become a serious discussion until they were married, well established in their careers and owned a home.

"Finishing school was never a question in either of our minds. I definitely wanted a home before I started a family. I wanted to be in a place where I wasn’t worried about my job or career," he said. "Solidifying those things in our lives was definitely important."

Therein lies the crux of this emerging trend, according to experts on marriage and childbirth.

Ryan Stotler and his girlfriend, Elizabeth Warner, live in Montclair. They represent an emerging trend in New Jersey -- young couples are putting off marriage and children.

"The main thing is the changes in the economy," said Kay Hymowitz, a researcher at the Manhattan Institute who has spent much of her career studying changes in marriage and childbirth in the United States. "You now need much more education, hopefully a college degree or even more, to maintain a middle-class lifestyle. That takes you well into your 20s. People want time to establish their careers, and careers are very demanding in their early years. You talk to young workers and they’re working 50, 60 hours a week when they start. That puts off marriage. Particularly among the college-educated, it puts off having children as well. That’s sort of a cultural shift."

The average age of a New Jersey mother when her first child is born has grown by nearly five years since 1970, according to the U.S. Centers for Disease Control and Prevention, and now stands at more than 27 years old, among the highest in the nation. Laura Occhipinti, founder of the networking group New Jersey Young Professionals, which caters to people 21 to 39 years old, says her organization has nearly 550 married members, virtually none of whom has children.

"They are waiting to get married, then waiting as long as they can to have children. People are pushing it as far as they can," she said.

Occhipinti said, by and large, urban centers are also far more attractive to her members than suburban and rural areas, and many planning experts believe a shift has started against the outward expansion of suburban sprawl back toward the nation’s urban cores.

"If a member does not live in a city they usually live in a bordering town," she said.

Ryan Stotler, a 35-year-old who recently purchased his first home in Montclair with his girlfriend, said the societal pressure to become successful played a role in his decision to put off children.

"There was this kind of threshold we felt we needed to get to," said Stotler, who has been with his girlfriend, Elizabeth Warner, for eight years. "I think there’s a lot of pressure now to be successful and attain status, perhaps more so than there ever was."

Hymowitz said the trend of having children later isn’t nearly as prevalent in couples with less education, and consequently, lower-paying jobs. But New Jersey is among the costliest states in the nation in which to live, and Realtors and real estate brokers interviewed by The Star-Ledger said, increasingly, they are seeing young couples eager to start a family leaving the Garden State to do so.

"A lot of them are leaving the state entirely," said Joan Barrett, a Realtor at Stanton Company Realtors in Montclair. "They want to have children, but they’re choosing to live elsewhere where the cost of living is less."

Hughes, of the Bloustein School, said New Jersey has been losing middle-class population from the suburbs to other states for many years as the state’s job market has changed and the cost of living has risen.

He said the nature of the suburban family as we know it has undergone a transformation over the past half century.

"The Ozzie and Harriet family, the husband, wife, two-point whatever children and a dog now is certainly less than 25 percent (of households). Back in 1960 it was closer to 50 percent. So what we think of as a traditional married couple family went from about half to about a quarter," Hughes said. "There has been a threshold change in the whole social fabric."

But while that image has shifted dramatically, to the Martins, it doesn’t mean attitudes toward family life have.

"We always wanted to have a family, but the time had to be right," Nate Martin said. "You come to an age where essentially you have to say to yourself ‘yes or no.’ We said yes."

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