be (one's) baby(redirected from be his baby)
be (one's) baby
To be something that one is closely involved with, such as a project or problem. That initiative is Cheryl's baby, so all questions can be directed to her.
be someone's baby
If you say that something is someone's baby, you mean that they have created it or are responsible for it. He's open to ideas for the movie, but it's his baby. There's no doubt Fashion Week is her baby.