Chicago ? All Alison Miller and Todd Parrish wanted was to become parents. But when a fertility clinic didn’t preserve an embryo they had hoped would one day become their child, they sued for wrongful death.

A judge refused to dismiss their case, ruling in effect that a test-tube embryo is a human being and that the lawsuit can go forward.

Though most legal experts believe the ruling will be overturned, some in the fertility business worry it could have a chilling effect, threatening everything from in vitro fertilization to abortion rights and embryonic stem cell research.

“If the decision stands, it could essentially end in vitro fertilization,” said Dr. Robert Schenken, president of the American Society for Reproductive Medicine. Few doctors would risk offering the procedure if any accident that harmed the embryo could result in a wrongful death lawsuit, said Schenken, chairman of obstetrics and gynecology at the University of Texas in San Antonio.

The lawyer for the clinic, James Kopriva, declined to say whether an appeal was planned, but added, “We disagree with the court’s decision and do not believe Illinois law provides for the remedy provided by the court.”

In a letter to the couple in June 2000, Dr. Norbert Gleicher, director of the Center for Human Reproduction, said an employee had failed to put an embryo in frozen storage and he apologized for “this oversight.”

The judge refers in his ruling to an Illinois statute that implies that wrongful death lawsuits can be filed on behalf of the unborn regardless of age.

There are nearly half a million such embryos frozen at fertility clinics nationwide. Most clinics keep them indefinitely until couples decide to use them or authorize their disposal, said University of Minnesota ethicist Jeffrey Kahn.

Miller and Parrish had no intent beyond seeking justice for the clinic’s error, said their attorney James Costello.