If he's WFH why can't he do housework on his breaks?
I'm WFH and I take a flask of coffee and some snacks/my breakfast/lunch etc first thing on a morning and midday so I can eat as I work and then my breaks are my breaks to do what ever it is that I need to do.
I load/unload the dishwasher. I will put tea in the slow cooker or get meat out to defrost for later. I bang a load of washing in ready to be put on the radiators when I'm finished.
There's absolutely no reason why, just because you're on maternity leave, he should reduce the amount of household responsibility he is giving.
Having a child is just an additional responsibility. And as there is only so much time in the day, that child is your main responsibility, anything else and his standards need to drop, or he needs to shut up and do it himself.
You're not responsible for more, just because he hasn't figured out a way to manage his time now his life has changed.
Of course, structure that constructively to him. A decent, respectable man will listen, talk, discuss, compromise, and won't lay blame or point fingers.
An indecent man will get defensive, blame, point fingers, maybe even shout, sulk, mope, etc.
Don't waste your time with an indecent man
Sincerely, all of us who've been there and done that.