Ashton Kutcher is being extra protective of Mila Kunis during her pregnancy.

The 36-year-old actor has reportedly been warning people not to stress out his fiancée, who is due to give birth in October, as he's worried pressure could affect the baby.

A source told the National Enquirer: ''Ashton is tense and always yelling, not only at photographers who get near Mila, but even at their friends who visit, telling them they're making too much noise. Mila keeps assuring him she's fine and doesn't need special treatment or peace and quiet, but Ashton acts like he's already pacing the maternity ward floors - even though she's not due for many weeks.''

The 'Black Swan' star recently revealed she loves being pregnant and is embracing her changing body, particularly her bigger boobs.

She said: ''They're amazing! They've tripled in size. I was a 34A; now I'm a 36C. I'm so excited! I'm telling everyone I know, 'Go ahead, touch them!' Without being an a*****e, I have to say, I love being pregnant.''

The 30-year-old actress is planning to have a natural birth with Ashton by her side, but she has already told her beau that he must stay ''above the action'' when their baby girl starts to make her appearance.