The proud parents, who worked on the popular Netflix horror series together, announced the birth of their second child on Monday.
"Today, Kate and I welcomed our daughter, Theodora Isabelle Irene Flanagan, into the world," Flanagan wrote. "Mom and baby are both fantastic, tired, and so, so happy."
Today, Kate and I welcomed our daughter, Theodora Isabelle Irene Flanagan, into the world. Mom and baby are both fantastic, tired, and so, so happy.— Mike Flanagan (@flanaganfilm) December 3, 2018
The baby's name, "Theodora," appears to be taken from Siegel's character from the Netflix Original, Theodora Crain. Theodora is also the name of a character in the Shirley Jackson novel of the same name that the show is loosely based on.
The newest addition joins the couple’s 2-year-old son Cody Paul Flanagan, whom they welcomed in 2016, and comes shortly after the actress revealed on Twitter that she had achieved a major accomplishment at 39 weeks pregnant.
“Successfully shaved the bottom half of one of my legs at 39 weeks pregnant,” she jokingly announced on Nov. 21.
The couple, who tied the knot in February of 2016, had initially learned of their pregnancy while in the midst of filming The Haunting of Hill House, with Siegel revealing in an interview with SyFy Wire in October that she learned she was pregnant during filming for episode six, “Two Storms.”
“Hilariously, I found out that I was pregnant while we were filming Episode 6. That long one-take episode where I have to fall down," she said. “I was working out with our stunt coordinator, and we were doing it over and over and over again. And there had been some interesting math with my cycle, so I was like, 'You know what? I'm just going to take a test to make sure.' And I told Mike that night, because we were going to be shooting the episode the next day, and the terror in his face was like nothing I had ever seen! He was like, 'I've just been throwing my pregnant wife on the ground all day!'"
After learning of the news, Flanagan admitted in a tweet that it made him “really nervous every time I saw her fall down. Added a special layer of nerves to the stress of the ep.”
Siegel also said that she was sick while filming her Red Room scenes. In between takes of the Red Room fantasy in which she was in bed with Trish, she had to “go puke in a trashcan.”
Siegel has starred in a number of her husband’s films, the two having initially met on Flanagan's 2013 movie Oculus. They went on to co-write his 2016 horror movie Hush, in which Siegel starred as the main character. She has also starred in Flanagan's adaptation of Stephen King's Gerald's Game, a film in which she was also pregnant during filming.