WASHINGTON — Anti-abortion advocates are cheering a provision in the new House GOP tax bill that explicitly states unborn children are eligible for tax-advantaged 529 college savings plans.

The language doesn't represent a change to existing law, as prospective parents can already open the accounts even before they conceive. But abortion opponents say the provision strengthens the argument that unborn children should be treated as people and given equal protection under the law — a key element in their battle to overturn or nullify the Supreme Court's 1973 Roe v. Wade decision that guaranteed a woman's right to choose to terminate her pregnancy.

"It's a small increment in the momentum that we're building to ensure that one day every child is welcomed and protected under the law," said Mallory Quigley, the communications director for the anti-abortion group Susan B. Anthony List. "We hope that it stays in the House bill and that it stays in anything the Senate puts out."

The bill defines an "unborn child" as "a member of the species homo sapiens, at any stage of development who is carried in the womb" — terminology that mirrors a section of the 2004 Unborn Victims of Violence Act, which was enacted after the murder of Laci Peterson, who was pregnant.

The 529 provision is a tiny section of a sweeping $1.51 trillion overhaul of the tax code unveiled by House Republicans on Thursday. Senate tax writers are expected to release their version soon, and the two chambers will have to pass their respective bills and then reconcile the differences to enact a new tax law.

Supporters of abortion rights adamantly oppose the provision.

"It is absurd that House Republican leaders would use a tax bill to try to advance their relentless agenda to undermine access to safe, legal abortion," said Kevin Griffis, vice president of communications for Planned Parenthood. "Denying women access to safe, legal abortion is wildly out of touch with the majority of Americans. Politicians in Washington, D.C., have no place inserting themselves in decisions about women's health and lives, not on this bill and not on any bill."