A California couple has filed a lawsuit over what has been described as one of the worst IVF mix-ups, that led to another woman giving birth to their son.

Anni and Ashot Manukyan, of the Los Angeles suburb of Glendale, said their life was upended after their embryos as well as those of two other couples were mishandled by CHA Fertility Center.

As a result, they said a complete stranger in New York gave birth to their child in March after two embryos - theirs and one belonging to another unidentified couple - were mistakenly implanted into the woman's uterus.

The New York woman, who is of Korean-American descent, was expecting to give birth to twin girls but ended up with two boys.

The Manukyans told reporters yesterday that they were unaware they had a son until the clinic, located in the Los Angeles area, contacted them out of the blue to obtain their DNA so that it could determine whether the child born to the New York couple was theirs.

Adding insult to injury, Ms Manukyan later learned that she had been implanted with an embryo - which failed to result in a pregnancy - belonging to another couple who were also clients of the fertility clinic.

The Manukyans said that following a protracted legal battle they finally gained custody of their son in May, when he was six weeks old.

"CHA put three families through a living hell, and our lives will never be the same," Ashot Manukyan told reporters.

"We fought to get our boy back, and now we will fight to make sure this never happens again."

His wife appeared emotional at the press conference, saying the ordeal has been traumatic.

"Who wants to meet their child in the lobby of a hotel?" Anni Manukyan said. "It was just heartbreaking. It was terrible." 

Adam Wolf, an attorney representing the couple, told AFP that the mix-up was "one of the worst fertility centre tragedies I have ever seen."

A woman who answered the phone at the clinic yesterday afternoon said the facility had shut down early for the day and no representatives were available for comment.

The New York couple involved in the mix-up have also filed a suit in federal court in Brooklyn, seeking compensation after suffering what they say are "significant and permanent emotional injuries from which they will not recover."

The pair, who are only identified by their initials in the court documents, began in-vitro fertilisation treatment at the CHA Fertility Center in January 2018.

Eight embryos were created on their behalf.

A first implantation in July 2018 was unsuccessful, but a second effort the following month worked, and the woman became pregnant with what she believed to be twin girls.

But doubts arose after the first sonograms, which showed the foetuses were boys. The couple were confused, as only one of the eight embryos was male.

Doctors at the clinic "assured them they were girls and that there was nothing wrong," according to the court complaint.

In March this year, the woman gave birth via caesarean section to two boys, "neither of which was of Asian descent," as the parents are. 

Genetic testing confirmed that neither the man nor the woman "was genetically related to the babies... and that the two male babies were not genetically related to each other," the complaint says.

The plaintiffs still do not know what became of their embryos.

"Defendants are concealing the whereabouts of the plaintiffs' two embryos ... They believe they were never thawed and/or lost or destroyed by defendants," the complaint says.

The couple is suing the clinic and two of their doctors, Joshua Berger and Simon Hong, alleging professional error, negligence, breach of contract and false advertising.

They are asking to be reimbursed the more than $100,000 they paid for treatment, their future medical expenses, lost wages and punitive damages.

After the babies were born, the clinic tracked down the Manukyans and the parents of the other baby who have also taken custody of their child.

Mr Wolf said his clients still have no idea whose embryos CHA inserted into Ms Manukyans's uterus.
"They have been unwilling to tell us how this happened," he said.