DES MOINES, Iowa (AP) – At least 21 Iowans in the last five years have obtained new birth certificates after undergoing sex-change operations.

They’ve been able rewrite the story of their births under a 28-year-old state law that allows sex-change recipients to petition for new birth certificates that show their new gender.

While those who got new birth certificates declined comment or didn’t return phone calls, supporters said the law simply grants them official identification that reflects who they really are.

“Certainly, getting pulled over and your driver’s license doesn’t match is a fear,” said Jordan Selha, who used to help run a transgender support group. “Changing the birth certificate is necessary to change other documents.”

Iowa’s 21st birth certificate change since 1999 was approved by a Polk County judge last month. Lawyers in Des Moines are working on at least one additional case.

Sharon Malheiro, a Des Moines attorney who heads a resource group for gays, lesbians, bisexual and transgender people said she thinks the increase in cases is part of a gradual trend.

“I think we’re in a different place today than we were 15 or 20 years ago in terms of acceptance,” Malheiro said. “I don’t know if acceptance is really the right word… but transgendered people are starting to live their lives.”

There are similar laws, though with varying forms, in 47 states. Only Idaho, Ohio and Tennessee do not provide any procedure for sex-changed individuals to alter birth certificates.

Gov. Robert Ray signed Iowa’s law in 1976, ordering the state registrar to create a new certificate for anyone who presented a doctor’s affidavit stating their gender had changed. Once a new document is created, only the person involved and his or her immediate relatives have access to the original paperwork.

“The old one is sealed,” said Iowa Department of Public Health spokesperson Kevin Teale. “Nobody would have any indication that there was a change involved.”

Selha said few transgender people actively try to conceal their original gender. Rather, changing the identification is the only way to avoid constant questions.

“I think it’s especially complicated when you look at someone traveling abroad,” Selha said. “A passport that doesn’t match your gender these days would be a problem.”

Selha said a growing number of resources have made it more likely that any Iowan who wants a sex change will stay in the state rather than move away as the medical process runs its course.

“There actually are physicians here now and therapists who will work with transgendered clients,” Selha said.