Jason Sudeikis reportedly fainted while Olivia Wilde was giving birth.

The 38-year-old actor was determined to support his fiancée throughout her entire labour with their first son, Otis, in April but at one stage he passed out in the delivering room.

A source told National Enquirer magazine: ''Jason was in the delivery room for Olivia, but witnessing and assisting in the birth suddenly became too overwhelming when he took one look at his child starting to be born, turned pale, mumbled something to a nurse and then went down for the count.''

The 'We're The Millers' star was worried he had missed his son's arrival after regaining conscious, but was assured by two nurses that he hadn't and then stepped back into the fray to support Olivia, 30.

The source added: ''Jason was totally fine from that moment on, endlessly tending to exhausted-but-ecstatic new momma Olivia and their bouncing baby boy.''

The proud mother and father have been enjoying every aspect of parenthood so far, and have already enjoyed some hilarious moments with baby Otis.

'Drinking Buddies' star Olivia recently revealed that Otis peed on his own face whilst she was changing his diaper.

She wrote on Twitter: ''Having an infant son alerts me to the fact that every man, at one point, has peed on his own face. #awesome (sic)''