The recent announcement that Scarlett Johansson is pregnant with her first child has lead to questions over her commitments to the upcoming "Avengers: Age of Ultron" which has just begun production.
Johansson is scheduled to give birth late Summer, and now a source close to production claims an initiative is already in place with director Joss Whedon and his crew set to fast track her scenes.
Johansson is currently in the midst of a "Captain America: The Winter Soldier" press tour and can't arrive on-set any sooner than April 5th. Once she's there though, it's likely they will shoot her scenes right away as Black Widow is expected to have a substantially bigger part in the movie.
Marvel is also famous for additional pick-up shooting closer to release with Johansson conceivably filming some of her more demanding scenes around year's end/early 2015.
Source: E! Online