Whereabouts are you and how many children do you have? How many are you planning? We're in London, I'm in a good job, and financially we will be far better off if I don't go back to work when DC2 arrives (I did go back after DS). Two lots of childcare, or one nanny, would wipe out my after-tax salary (because (apart from childcare vouchers, which are capped) you earn your money, pay tax and NI on it, THEN have to finance childcare out of net salary. And if you are having a nanny you are an employer and need to pay tax and NI on what you are paying her, as well as paying her salary).
Do the sums... it may well be that your going back to work doesn't bring in as much extra money as he thinks, when all the childcare costs are factored in, and potentially it could lose you money. And when he looks at that offset against the lifestyle compromises he'd have to make if he wants to split the child-related stuff evenly, my suspicion is that he won't think it's worth it (unless you are earning pots and pots of money).
You do need to be firm, though, that if you go back he will be doing half of all that stuff. And make sure he fully understands what it is
Getting DCs to childcare before work
Picking up DCs from childcare after work
Dealing with sick DCs who can't go to childcare/school
Taking vacation time to cover school holidays
Taking DCs to the dr / dentist/ optician
Buying toys
Buying clothes
Buying shoes
Buying things for DCs' rooms
Buying gifts for DCs to give to others
Laundry including ironing (his own, plus 50% of DCs')
Cooking (50% of all meals)
Dishes and putting away (50%)
Vacuuming (50%)
Cleaning bathrooms (50%)
All the other household stuff that temporarily escapes me (50%)
My guess is that he will backtrack very quickly...