Every time I'm at my D&D game the hosts baby ruins it so I'm going to tell them about this issue.
What is wrong with their baby?
It is stupid and it keeps whining.
You should know that babies cry all of the time. I am sure the parents are aware of their baby, there is no need to tell them that.
They need to focus on their bloody baby and doing better for their child so it will be less annoying.
While you may be a little bit annoyed by a babies crying, they can't really do anything to prevent someone so young from acting out. You could offer to host the next D&D session instead of complaining about their child?