NEW YORK — Child marriage wasn’t an issue of note for Virginia state Senator Jill Vogel until she heard the stories circulating in her district about a man in his early 50s marrying a girl in her mid-teens, warding off a police investigation of his relationship with her.

Now Vogel is lead sponsor of a bill advancing in Virginia’s Legislature that would sharply curtail child marriage.

‘‘Our marriage laws in Virginia are not protecting children,’’ she said.

A similar measure has been introduced in Maryland, and a pending bill in New York goes even further — it would make the state the first to ban marriage altogether for anyone under 18.

Worldwide, child marriage is a reality for millions of girls. Though the practice is most common in developing countries, critics who argue it exposes many girls to emotional and even physical harm say it poses a largely unseen threat in the United States as well.

‘‘We think we’re so sophisticated, so progressive and ahead of the times, and yet we still see this barbaric behavior,’’ said Assemblywoman Amy Paulin, sponsor of the bill in New York.

Across the United States, states laws generally set 18 as the minimum age for marriage, yet every state allows exceptions. Most states let 16- and 17-year-olds marry if they have parental consent, and several states — including New York, Virginia, and Maryland — allow children under 16 to marry if a court official gives approval.

There are no nationwide statistics on child marriage in the United States, but data suggests it is far from rare.

Fraidy Reiss, who campaigns against coerced marriage as head of a nonprofit called Unchained at Last, researched data from her home state of New Jersey, and determined that 3,499 minors — 90 percent of them girls — were married in the state between 1995 and 2012, including 178 who were under 15.

In New York State, according to Reiss, 3,853 minors were married between 2000 and 2010. Her figures came from state health department data.

In Virginia, state health statistics show that over 4,500 minors were married between 2000 and 2013, including about 220 who were 15 or younger.

Such data ‘‘should set off alarm bells, not wedding bells,’’ said Jeanne Smoot, senior counsel for policy with the Tahirih Justice Center in Falls Church, Va., which assists women at risk of domestic violence, trafficking, and forced marriage.

Reiss — who says she was forced into an abusive marriage by her Orthodox Jewish family when she was 19 — contends that cases of child marriage via parental consent often involve coercion, with a girl forced to marry against her will. She says states generally do not require any investigation of this possibility, and girls are often not asked if they are marrying voluntarily.

Inspired by Reiss’ efforts, Paulin, the New York legislator, introduced a bill in January that would eliminate all exceptions in New York’s statutes and prohibit the marriage of anyone under 18. Paulin, a Democrat, believes her bill can get bipartisan support and become law.

‘‘Just because we’re not talking about millions of girls here in the US doesn’t mean we shouldn’t protect the thousands of girls who are affected,’’ she said.

Reiss has been in touch with lawmakers in New Jersey, hoping for similar legislation there.

‘‘Mostly the response is, ‘I can’t believe this is happening in my state. We have to stop it,’ ’’ Reiss said.

Meanwhile, the Tahirih Justice Center is working with legislators in Virginia to enact a law barring all under-18 marriages except for cases where 16- or 17-year-olds acquire the rights of an adult via an emancipation order freeing them from the control of their parents or guardians.