WASHINGTON - States may classify a developing fetus as an "unborn child" eligible for government health care, the Bush administration said yesterday, giving low-income women access to prenatal care and bolstering the arguments of abortion opponents.

The plan will make a fetus eligible for health care under the State Children's Health Insurance Program. Because CHIP is aimed at kids, it does not typically cover parents or pregnant women.

Health and Human Services Secretary Tommy Thompson cited well-established data on the importance of prenatal care in explaining the proposal.

"Prenatal care for women and their babies is a crucial part of the medical care every person should have through the course of their life cycle," Thompson said in a statement. "Prenatal services can be a vital, lifelong determinant of health, and we should do everything we can to make this care available for all pregnant women."

States that administer CHIP would have the option of including fetuses in their programs. Doing so would make the mother eligible for prenatal and delivery care.

Abortion rights supporters complain that there are other ways to include coverage for pregnant women in CHIP. They see yesterday's action as a backdoor attempt to establish the fetus as a person with legal standing, which could make it easier to criminalize abortion.

"If they're interested in covering pregnant women, why don't they talk about pregnant women?" asked Laurie Rubiner of the National Partnership for Women and Families. "I just have to believe their hidden agenda is to extend personhood to a fetus."

This plan, she said, "sets legal precedent on its head."

States may already cover pregnant women under the health program, though they have to get specific permission from HHS since CHIP was designed for children, not adults.

Thompson promotes these waivers as an excellent way of expanding health coverage to people without insurance. He regularly brags about speeding the time it takes for them to be approved by federal officials. But in his statement yesterday, he said automatically including the fetus is the quickest way to get prenatal services to the most women.

The waiver process "would take longer than extending it this way," said HHS spokesman Campbell Gardett.

Thompson said he also supports legislation pending in the Senate that would allow states to automatically add pregnant women to CHIP, much like poor pregnant women are eligible for Medicaid.

Administration officials said last summer that they were considering this policy change. At the time, the National Governors Association cautioned HHS that while some states would embrace the new option and some would immediately reject it, other states would face divisive battles over whether to go along.

The new policy will not take effect until after it is published in the Federal Register and the department considers public comments.