Women like Kate Hudson, Natalie Portman, Selma Blair, and Christina Applegate are all pregnant, but what else do they have in common? They’re also unmarried. This trend is and has been happening throughout Hollywood, but it hasn’t stopped there. The rate of unwed mothers in the United States has more than doubled since the 1980s.

Let the stats speak for themselves. Nearly four out of every ten births in our country are to unmarried women, which is a "huge increase — a dramatic increase," said Stephanie J. Ventura of the National Center for Health Statistics. "It’s quite striking."

Why the jump? Although the study did not report on the reasons for the rise, experts cite a combination of factors. People are increasingly delaying marriage or not getting married at all, and the social stigma associated with umarried motherhood is dwindling. In addition, many financially independent women and older and single women are saying to themselves, "Hey, I’ve waited long enough for Mr. Right and he hasn’t come along, so I’ll just have a kid myself!"

"I think this is the tipping point," commented Professor Rosanna Hertz of the Wellesley College sociology and women’s studies departments. "This is becoming increasingly the norm. The old adage that ‘first comes love, then comes marriage, then comes baby in the baby carriage’ just no longer holds true."

Some experts are in support of this growing trend. They claim that it represents a positive change for women — they can raise their children in nontraditional families without be treated as social outcasts or feeling like they have to give up their babies for adoption or get abortions.

At the same time, others cite numerous experiences in which children tend to be worse off in many ways when raised without a stable, two-parent home.

According to the report, about 1.7 million babies were born to unmarried women in 2007, which constitutes a 26 percent rise from 1.4 million in 2002 and more than double what it was in 1980. In 2007, unmarried women accounted for 39.7 percent of all U.S. births, while it was just 34 percent in 2002 and less than half that percentage three decades ago

Much of the rise in numbers is driven by women in their 20s and 30s. However, older teenagers seem to be following suit, a path that concerns experts because the increase in births comes after years of steady decline.

Hispanics and blacks showed the highest increase in births to unmarried women, followed by whites and then Asians. It seems that the United States’ birth rate to unwed mothers is beginning to mirror Europe’s. For instance, this proportion is about 66 percent in Iceland, 55 percent in Sweden, 50 percent in France, and 44 percent in the United Kingdom.

In many of those countries, couples live together without ever getting married, which seems to be a growing practice in the US as well, according to the report. Many couples in this situation fail to see the point in getting married just because they are having a child together.

"It seems to be more wrong to be in a marriage with someone who you don’t love and consider to be your best friend than not to be in a marriage at all," said Barbara Katz Rothman, a professor of sociology at the City University of New York. "It’s not that people care less about marriage. In some ways, it’s because they care more."