Let's face it.
Zombies are attracted by sound.
Your baby makes a LOT of sound. And it requires to be fed, and to have medicines that would get you in a lot of danger to seek for.
Would you kill your baby and hope to make another one later on better days,
or would you be ready to have both of you killed and turned to zombies ?
My opinion is simple. It would be hard, but I would do it. If my wife doesn't want to and is in denial, well, she can go carry him over... Outside.