Thomas Beatie, the transgender man who bore a daughter four months ago, has become the public face of an issue for many other transgender people: having their roles as parents legally recognized.
In an exclusive interview airing tonight on "20/20," Beatie told Barbara Walters that he is pregnant with his second child.
After the birth of their baby girl, Susan, in June, Thomas Beatie, 34, and his wife, Nancy, 46, of Bend, Ore., found themselves in a legal thicket that serves as a cautionary tale for other transgender families.
Thomas Beatie is legally male. But as the parent who gave birth, he was listed by the state of Oregon on the birth certificate as the "mother." His spouse was then listed as their baby's "father."
Later, those designations were scrapped by the state for the gender-neutral term "parent," which is commonly used on the birth certificates of children of same-sex couples. For the Beaties, this was still upsetting.
"In essence, they are invalidating our marriage," Thomas Beatie said. "It is very upsetting to me. I feel that it's a flawed document."
When asked whether he sees himself as Susan's father or her mother, Thomas Beatie said, "I am my daughter's father, and that's all I'll ever be to her. Nancy is Susan's mother.
"It just goes to prove that mother and father are social terms," he said. "You don't have to be biologically related to your child to be a mother or a father."
Suzanne Goldberg, who directs the Sexuality and Gender Law Clinic at Columbia University in New York City, sympathizes with the Beaties' frustrations but says they should not be overly concerned about how they are listed on the birth certificate.
"It's hard to imagine a birth certificate being used as a basis to challenge a marriage," Goldberg said.
"What matters is that the adults involved are designated as 'parent.' It doesn't matter legally whether one adult is called 'mother' or 'father.' Those are social categories. They don't have legal meaning in this context."
The potential trouble spot, according to legal experts, is not the wording on the birth certificate but the possibility that Nancy Beatie's parental rights could be revoked.
As the biological parent, Thomas Beatie has legally secure rights. His wife, on the other hand, is not biologically related to their baby but is granted parental rights by virtue of her marriage to Thomas Beatie.
So if the validity of their marriage were challenged, experts say, Nancy Beatie's parental rights could be in jeopardy.
"There is litigation in other states over whether their marriage would be recognized," said Nancy Polikoff, a law professor at American University in Washington, D.C.
Polikoff envisioned a scenario in which the Beaties moved to a state that refuses to recognize Thomas Beatie's legal sex change in Hawaii. If that happens, his marriage would be revoked as an illegal same-sex marriage and Nancy Beatie's parental status could be questioned.
That would be a nightmare for the Beaties.
"Oh, I think we're very worried," Nancy Beatie said. "We're both very worried."
Said Thomas Beatie: "If something were to happen to me, I want to make sure that Nancy has custody over her daughter."
In 2002, when he was already in a relationship with Nancy, Thomas Beatie had sex reassignment surgery to remove his breasts.