"I carried my own child. I didn't know he was mine." That's what a California woman is saying after she became pregnant with her own son while serving as a surrogate for a Chinese couple. After connecting with the couple through a surrogacy agency in California, Jessica Allen, 31, was implanted with an embryo in April 2016, reports ABC News. Six weeks later, Allen was told she was expecting twins and assumed the embryo had split in two. But that wasn't in fact the case. A month after Allen gave birth in December, a DNA test showed one of the two babies had developed from the embryo, while the other was Allen's biological child, reports the New York Post. "We were floored," says Allen, who, in a rare case of superfetation, had become pregnant while already pregnant, per ABC.
A doctor tells Live Science that fewer than a dozen cases of superfetation are recorded in medical literature. Though more cases may go unreported or even unnoticed, superfetation is extremely uncommon because, for one thing, a woman usually stops ovulating when pregnant. After Allen was implanted with the embryo, however, her ovaries released another egg that was fertilized. Allen had no contact with the two infants immediately after birth, but she says she knew they weren't twins when she saw a photo showing "one was much lighter than the other," per ABC; Allen is white, while her husband is black. The Post describes the complicated legal battle that followed before the couple gained custody of their son in February. They now describe him as an unexpected treasure. (An "angel" surrogate delivered actual twins.)