Too busy with baby to lead a project?

I didn’t think my boss would treat me differently after finding out I’m pregnant since she is a woman and has gone through this before, but there’s a project that starts after I’m back from maternity leave that I offered to take over from someone who doesn’t want to work on it next year and my boss said she thinks I’ll be too busy with my new baby to lead the project. She’s still advocating for a promotion for me, but doesn’t want me to lead this project and I don’t understand why. I’m still going to work full time when I’m back, so there’s no reason why I couldn’t lead this project.