They already have two daughters together- Lily Grace Victoria, 5, and Theodora “Teddy” Marilyn, 4.
In the picture posted, the baby’s eyes are already open, laying connected to the tubes while a nurse seems to be working on him.
Munn and Mulaney sparked rumors of the affair after they were pictured together at a lunch in June 2020.
The news of the high-profile couple comes just days after Schwarzenegger celebrated her 32nd birthday.
Tristan Thompson did acknowledge being intimate with Nichols at a hotel several times after attending a party back in March.
“I decided to have a baby on my own. Because it’s all I’ve ever wanted and life is short."