Fewer twentysomethings are tying the knot according to a new study.

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A recent Urban Institute report finds that millennials are on track to have the lowest rates of marriage by the age of 40 compared to any previous generation. If the pace continues, more than 30 percent of millennial women will remain unmarried by the age of 40, nearly twice the number of their Generation X counterparts.

These days, couples tend to move in together and raise children without the commitment of marriage.

"There is less and less pressure on young couples to get married," said Marty Tashman, a licensed marriage and family counselor in Somerset, New Jersey. "Women are not having children quite so young and are instead developing careers for personal and financial reasons. We are also getting less and less religious, so we no longer have that pressure."

Those who do get married are doing so later in life when they are established financially. It used to be that marriage was a starting point for young couples. Marriage rates fell even more during the recession, during which young adults had a tough time getting work and many others were collecting unemployment.

Just how many millennials get married by the time they turn 40 will depend on whether marriage rates return to pre-recession levels. According to the study, only 69.3 percent of women will marry if the post-recession rate continues, while 76.8 percent will if the rate returns to pre-downturn levels. For men, the rates come in at 65 percent and 72.6 percent, respectively. That compares to 82 percent of Generation X women and 76.6 percent of Generation X men who were married by 40.

Married couples are usually better off financially and can generally spend more. Singles are less likely to buy homes. While the study implies that having more singles could have an impact on the economy, Tashman is not convinced.

"It'll put more people into the workplace because women are defining themselves less as being parents and more as having careers," he said. "So, it'll likely raise the competition, so it may hurt the economy in that way."

Tashman added that as millennials make more money, they'll become better consumers, buying different things than their married counterparts.

What about a societal impact?

"When you make a commitment to someone in front of your friends and family and God, there is more of a formal commitment," Tashman said. "If you're not married, it's much easier to separate. You don't have to deal with the courts and property. When you're married, it's not only a religious commitment, it's a legal commitment as well. The root of the strength of society is having strong families and without being married, it weakens the possibility of a strong family."