Tom Cruise was Rosamund Pike's ''protector'' when the pair filmed Jack Reacher.
The actress was five months pregnant when she shot the thriller and she was touched by how ''supportive'' her A-list co-star was on set as she knew there was a chance she could have been replaced on the project.
She said: ''He could not have been more supportive. Certain stars would have - or might have - said, 'Get someone else, she's pregnant!' That sort of thing goes on in this day and age."
'You don't know if you're going to have terrible morning sickness, whether you're going to suddenly balloon. I felt as if I had a secret stowaway. Tom was protective in a way I didn't expect. Sometimes you think after 30 years the performance might all be just for the camera - but you get all of it with Tom. Everybody gets all of it.''
The 33-year-old actress - who gave birth to Solo, her first child with partner Robie Uniacke, in May - is amazed her son is so ''chilled'' as the film meant she was shooting scenes involving high-speed car chases, being tied up and having a gun held to her head while she was expecting.
She told the Daily Mail newspaper: ''It's amazing the baby's come out so chilled. He probably thought the world was going to be truly terrifying. He came out, this delightful child, thinking, 'Thank God for that! I thought the world was going to be full of evil people with guns and bullet ridden cars!' ''