A woman who donated her eggs to her lesbian partner has no parental rights over the twin girls they produced, a California appeal court has ruled.

The ruling, issued late on Tuesday, incensed lesbian rights groups that are already embroiled in court battles in California over the legal status of hundreds of same-sex weddings conducted in San Francisco in February and March.

The twin girls were born in December 1995 after the eggs, donated by a woman identified as K.M., were artificially inseminated and implanted in her lesbian partner, identified as E.G., in a San Francisco hospital.

The couple and the twin girls lived together for five years until K.M. decided she wanted to adopt the twins and their birth mother decided to move with the twins to Massachusetts.

The National Center for Lesbian Rights said it was “extremely disappointed” by the ruling.

“There is no question under California law that K.M. would be a legal parent,” said legal director attorney Shannon Minter. “It is cruel to the children to deprive them of one of their parents solely because she happens to be a lesbian.

“Are we going to apply the same rules to lesbian couples as we do to heterosexuals or will the California courts treat non-biological lesbian mothers as strangers to their own children?” Minter said.

Minter said the case is likely to be appealed to the California Supreme Court.

The California Court of Appeal ruled that the two women had a prenatal agreement that the birth mother would be the legal parent. The court also decided that K.M. gave up her claim to parentage when she signed an egg donor consent form in 1995 for the procedure.

“What is legally relevant is the finding by the trial court that they intended E.G. to be the one to bring about the birth of a child to raise as her own child,” wrote Justice Mark Simons in a 3-to-0 ruling.

Simons also noted that the couple did not begin adoption proceedings at the time of the twins’ birth and that in their absence, “any post-conception revision of the natural mother’s intentions is legally irrelevant.”

The ruling was handed down days ahead of a California Supreme Court hearing later this month stemming from two of the more than 4,000 same sex couples who married in San Francisco in February and March.

The validity of the marriages is in limbo since the California Supreme Court ordered the liberal city to stop issuing marriage licenses. The legal dispute involves a California law that defines marriage as between a man and a woman, and equal protection guarantees defined in the U.S. Constitution.