Megan Fox appeared on "Ellen" and "Tonight Show with Jay Leno" this week to promote her upcoming film, "This Is 40."

In both interviews, she discussed several experiences during her pregnancy. She revealed how fellow actress Reese Witherspoon helped keep the birth of her baby Noah a secret and how her delivery process experience resembled the birthing scene in a "Twilight" film.

The "Transformers" star explained to Ellen DeGeneres how the 'Legally Blonde" actress unintentionally helped her deliver her first child in secret from the prying eyes of paparazzi. When Witherspoon went into labor the day before she did, the attention on the "Walk The Line" actress became the perfect diversion for Fox and her husband Brian Austin Green.

"She went into labor the day before I did, and all of the paparazzi followed her to Santa Monica," Fox told DeGeneres. "So when I went into labor, I went to Cedars [Sinai Medical Center in L.A.], and nobody cared or knew I was there. So I got in and out. I left the next day and nobody knew. It was a big secret for three weeks."

DeGeneres asked which parent their baby Noah, who turns three months this week, resembles more. Fox admitted he shares most of his father's good looks. "He looks, I would say, 70 percent like Brian," the new mom said. "He was his identical twin when he came out [but] recently he's been getting chubbier and everyone's like, 'Oh, he's so chubby -- now he looks like you. I don't know how I should take that," she joked.

Earlier this week, Fox told Jay Leno on 'Tonight Show" that the delivery process to give birth to her baby was so strenuous that it resembled a scene in a "Twilight" movie, when Bella gave birth to her vampire child.

"It was so bad for me, actually, that I felt like I was maybe birthing a vampire baby, like the one from 'Twilight,'" the "This is 40" star told Leno on Dec. 17. "You know what happens to Bella -- where she's in like cold sweats all the time? I felt like that was happening, because I had no vitamins and nutrients. I was just nauseous."

She also shared that the first trimester was pretty rough due to morning sickness. "I had pretty bad morning sickness," the brunette said. "The first trimester was really rough and then I got to about 12 weeks and then it was fine. It was a really perfect pregnancy after that."

Fox's interview on "Ellen" will air Wednesday, Dec. 19. 

"This Is 40" stars Fox alongside Leslie Mann, Paul Rudd, Jason Segel and Melissa McCarty. The Judd Apatow-helmed film arrives in theaters December 21.

Watch Megan Fox discuss baby Noah on "Ellen' with talk show host Ellen DeGeneres