Inside the couples shocking IVF deal that led them to have a baby in another family: What happened?

After mixing up at an IVF clinic , two California couples gave birth to and raised another couple’s child – a situation experts say is extremely rare.

In this week’s exclusive cover story , Alexander and Daphna Cardinale opened up to PEOPLE about the ordeal, which began shortly after Daphna gave birth to the couple’s second child in September 2019 – a daughter, to their surprise, it looked nothing like them.

That November, an at-home DNA test kit confirmed their child was not genetically related to either of them – and the following month, they discovered that another couple at the clinic (who did not want to be publicly identified) gave birth to a child through IVF, who also had no biological relationship to the parents.

Soon after, DNA confirmed the mistake and the couples made the difficult decision to agree to legally exchange their children.

What exactly happened and how did this happen? The Cardinals remain in the dark and are currently suing their physician, Dr. Eliran Mor, along with his fertility clinic, the California Center for Reproductive Health, as well as a laboratory owned by the defendant Mor accused of preparing to transfer their embryos, accusing them of malpractice, malpractice and fraud, among other things. (The office administrator at the clinic declined to comment to PEOPLE on this case.)

“Điều này cực kỳ hiếm”, chuyên gia IVF, Tiến sĩ Michael Alper, Giám đốc Y tế và Bác sĩ Nội tiết Sinh sản tại Boston IVF, người không liên quan đến vụ việc, nói với NGƯỜI DÂN trong vấn đề tuần này. “Khi tôi nghe về những thảm họa như thế này, nó thực sự ăn mòn trái tim tôi bởi vì tôi cảm thấy rất tồi tệ cho tất cả những người có liên quan.”

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Alexander and Daphna Cardinale; the couple on the cover of PEOPLE

IVF clinics generally double check everything to make sure a major mistake never happens, experts say.

“There’s really numerous safeguards that are put in place to keep the human error to an absolute minimum,” says Alper, an Associate Clinical Professor in the Department of Obstetrics, Gynecology and Reproductive Biology at Harvard Medical School.

RELATED: Couple’s ‘World Started Falling Apart’ After Discovering IVF Embryo Mixup: ‘This Isn’t Our Child’

Alper studied 181,800 cases looking for mistakes from small ones — like misspellings and typos — to extreme errors such as mixing up eggs, sperm or embryos.

His research found no extreme errors and 99.96 percent of the procedures had no small errors either.

“The vast majority of procedures are extremely safe in an IVF laboratory,” Alper says. “When somebody asks me, ‘Can you 100% guarantee there’ll never be an error?’ Nobody can say that for certain. But what you can say is, ‘We have a lot of systems in place to make that very unlikely.’ “

For more on the Cardinales’ ordeal, pick up the latest issue of PEOPLE, on newsstands Friday, or subscribe here.

Clinics generally have their own “very precise protocols” to ensure that “nothing is mixed up,” according to Dr. Nicole Noyes, a fertility-preservation and IVF specialist at Northwell Health in New York City.

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yuri hasegawa Alexander Cardinale and Daphna Cardinale with daughter

“There’s lots of different ways to keep things straight,” Noyes says.

Her clinics make use of a “spotter,” a technician whose job is to check, match and positively identify samples.

Another safeguard is to use color-coded labels for vials and lab dishes, because research shows that people remember color more than they remember names.

RELATED: IVF Embryo Mixup Leaves Two Couples Raising Each Other’s Babies: ‘It’s Still a Daily Struggle’

“That has been pretty fail safe,” she says. “I’ve been doing this 30 years, I’ve been involved in about 30,000 IVF cycles and I haven’t seen a mix up yet.”

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Yuri Hasegawa Alexander and Daphna Cardinale

Although Noyes is not involved in the California couple’s case and is unaware of the specific safeguards employed by the California facility, she says she saw a lot of red flags when reading about it online.

“Clearly this program did not have a fail-safe protocol in place,” says Noyes. “They obviously swapped the two samples at some point. And that’s really scary.”

Another source of concern, in Noyes’s view, is that there was a secondary lab involved.

“It sounds like there was some lack of clarity on who was actually responsible for the embryology care,” she adds. “We don’t have any secondary anything. Everything’s right here. We know what’s going on. And importantly, the patient knows what’s going on.”

Noyes says that the silver lining is both couples were able to successfully get pregnant. “They both wanted a baby, and they both got a baby,” she says.

“Carrying the wrong baby, raising the wrong baby for a month or a year or however long, and then swapping it out. It’s not like swapping out your earrings. I can do that in a heartbeat, but you wouldn’t do that with a child.”