A couple is fighting a Connecticut fertility clinic in court after they say the facility gave them the wrong embryo — and they wound up giving birth to a baby of another race.

The husband and wife, who now live in the UK, are suing the recently shuttered CT Fertility in Trumbell and Dr. Melvin Thornton, claiming the shocking mixup has left them with “haunting uncertainties regarding their second-born son.”

The pair first visited the clinic in 2015 while struggling to conceive and froze embryos using the husband’s sperm and eggs from a donor they specifically chose, according to their suit, which was first filed in a Bridgeport court in November.

The wife then became pregnant with the couple’s first child via in vitro fertilization — and gave birth to a boy in April 2016, the suit says.

They returned to the clinic in September 2016 in the hopes of giving their son a full sibling by using the embryos stored from the previous procedure.

But when the wife gave birth to another son in August 2018, the tot didn’t resemble his older brother “whatsoever” — and had “much darker skin pigmentation than either the father, genetic mother or their first son.”

Realizing something was very wrong, they ordered DNA tests — which gave the stunning result that their youngest child is not biologically related to the dad, according to court papers.

“While their second-born son is loved and healthy in every aspect, he is not in fact their biological baby,” court papers say.

They now live with a “constant, nagging and debilitating fear” that this mystery sperm donor will realize what happened and claim custody of their kid.

They also say the situation has left the family vulnerable to “ignorant and cruel harassment” from judgmental strangers.

“They are barraged daily with questions and suspicions regarding who the child’s real father is and even whether the [sic] mother had an affair,” the suit says.

And they’re worried about the fate of the rest of the sperm they gave to the clinic.

“They have reason to believe they have lost genetic material (embryos) belonging to them, with no knowledge as to whether it has been transferred to another person, destroyed or frozen under an incorrect name,” the suit reads.

In court papers filed earlier this month, the parents described the anguish that plagues them as they continue to pursue the case, which isn’t set to go to trial until September 2021.

“They are left with potential life-long haunting uncertainties regarding their second born son, and unknowns about what happened to their genetic material and where their genetic material ended up,” court papers said.

“Whose genetic material was transferred to the plaintiff? Is the child’s biological father a carrier of some sort of disease? What is the genetic makeup and background of the baby? Will someone one day attempt to make claim to the custody of their child?”

Lawyers for Thornton and CT Fertility didn’t immediately respond to requests for comment.

The couple’s attorney declined to comment.