"When I went home, I started to feel like... my tongue felt strange," said Chen of leaving the hospital.
"It felt a little tingly, just starting to get a little bit numb. And then I realized my face just felt weird. I didn't know what the feeling was that I was having. It felt weird."
King then asked if her face "looked different" when she looked in the mirror, which Chen confirmed was true.
"When I got home, it was like everything was starting to just fall down on itself. Like, my face was melting on itself," said Chen. "And then a week after giving birth, that was when it all hit."
"I was trying to eat," continued Chen. "I went to put a fork of food in my mouth and everything came out. I couldn't eat. And then I was starting to slur. So I said, 'There's something really going on here.'"
Chen was instructed to "go right to the hospital".
"I lost all facial function the minute I got to the hospital," she revealed.
Chen and De Niro, 79, welcomed daughter Gia Virginia earlier this year, and the actor shared some details about his newborn with King in a previous interview.
King said the child's name is Gia Virginia Chen-De Niro and weighed in at 8 pounds, 6 ounces after her April 6 birth.
King said De Niro told her the baby was "planned" and both he and Chen "wanted this baby." She added the two were "over the moon" by her arrival -- and said, "she was brought here by love, so he is very psyched and very excited about it."
De Niro now has seven children total, ranging in age from 51-years-old to just 1-month.
The actor shares daughter Drena, 51, and son Raphael, 46, with first wife Diahnne Abbott, twins Julian and Aaron, 27, with ex-girlfriend Toukie Smith and two children -- son Elliot, 24, and daughter Helen, 11 -- with Grace Hightower.