Only adults can get married in Virginia, according to a new law replacing policies that made it possible for a girl 13 or younger to marry if she had parental consent and was pregnant.

The law, which took effect Friday, sets the minimum marriage age at 18, or 16 if a child is emancipated by court order. It takes parents and pregnancy out of the equation.

The change is aimed at curbing forced marriage, human trafficking and statutory rape disguised as marriage. Activists say the previous law created a “fast-track to child marriages” for abusers who could evade investigation by child-welfare officials by simply marrying their victims.

Nearly 4,500 children under age 18 were married in Virginia from 2004 to 2013, according to data from the state’s Department of Health. That includes more than 200 children age 15 or younger.

[Here are some of the laws that took effect in Virginia and Maryland last week]

About 90 percent of the underage spouses were girls; in many cases, the girls married men age 21 or older, and sometimes the men were decades older, data show.

The statistics prompted the Falls Church-based Tahirih Justice Center, which works to end forced marriage in the United States, to set about getting the laws changed through a rare bipartisan effort.

Sen. Jill Holtzman Vogel (R-Fauquier) and Del. Jennifer L. McClellan (D-Richmond) sponsored identical bills that passed during this year’s legislative session, despite some opposition.

Similar bills were introduced in California, Maryland, New Jersey and New York this year, according to the National Conference of State Legislatures.

“We hope that legislators will see the efforts in Virginia as a wake-up call about how their laws can facilitate forced marriages of children,” said Jeanne Smoot, ­Tahirih’s senior counsel for policy and strategy.

Vogel said she learned about the issue when constituents in an affluent part of her Northern Virginia district sought her help after a man in his 50s was suspected of having sex with a high school student.

As child-protective services began to close in, Vogel said the man wooed the parents and married the girl, eliminating the possibility of prosecution. It was the second time he followed this tactic; the earlier marriage ended in divorce, she said.

“Now they’re married, and there’s no crime,” said Vogel, a lawyer who is running for lieutenant governor. “She dropped out of high school. Her life is ruined.”

When children get married, Smoot said, they are 50 percent less likely to finish high school, four times less likely to go to college and more likely to have children sooner and more closely spaced than people who marry as adults.

Underage brides are also more likely to experience mental and physical problems, Smoot said, and have a divorce rate of as high as 80 percent.

McClellan noted that her grandmother married at age 14 in Mississippi in the early 1900s, when it was more socially acceptable and before evidence showed the risks of underage marriage.

Today, she said, the new legislation was needed to bring consistency to child-safety policies and to close what advocates call a “gaping loophole” in marriage laws.

“Sex with a child is illegal,” McClellan said, “but the way the marriage laws worked, if you were under 16 and pregnant, rather than punishing your assailant, you were allowed to marry them.”

[Photos: ‘Saddest bride I have ever seen’: Child marriage in Bangladesh]

For these reasons, Tahirih is urging states to follow Virginia’s lead and set the minimum marriage age at 18.

In Maryland, children can get married at 16 and 17 with parental consent and 15 if there is a pregnancy. In at least 200 cases from 2000 to 2014, minors married spouses 10 years their senior, Smoot said.

A bill died in Annapolis this year, but lawmakers plan to try again next session.

In Virginia’s Republican-

controlled General Assembly, the law passed 65 to 29 in the House and 38 to 2 in the Senate and was signed by Gov. Terry McAuliffe (D).

Although the law sets the limit for the age of consent, a juvenile and domestic-relations district court can emancipate 16- and 17-year-olds who wish to marry if a judge finds the minor is not being compelled to marry, the parties are mature enough, the marriage will not endanger the minor and the marriage is in the best interest of the minor.

“Neither a past or current pregnancy of either individual to be married . . . nor the wishes of the parents or legal guardians of the minor” are enough to prove emancipation is necessary, the law says.

That’s troubling to opponents such as Sen. J. Chapman “Chap” Petersen (D-Fairfax), who said it is not for lawmakers to judge the decisions of pregnant teens and their families.

“Maybe I’m old-fashioned,” he said, “but if someone gets pregnant and they want to be married when the child is born, not being able to do that of their own volition without going to court, I thought that was a little bit overly aggressive.”

Del. David A. LaRock (R-

Loudoun) said he worried that pregnant teens could be more likely to have abortions if they must have court permission to marry.

“Ultimately, I was not convinced this was an effective way to fix the problems it was targeting like forced marriage and sex trafficking,” he said.

More than 700 million women worldwide were married as children — four times the female population of the United States, according to UNICEF.

The practice is on the decline around the globe as well as in Virginia, where the number of minors married dropped from about 800 in 2005 to about 200 in 2013, state data show.

But advocates at Tahirih worry that the minors still marrying today represent a particularly vulnerable subset of children with few, if any, other options.