Ok, so we have a joint account, which pays for all household bills and which soon will also pay for the extra expense that comes with a baby. We then have a joint savings account (currently with zero in) which is for spending on the house and holidays and seperate savings accounts (he has nearly 0, I have the money I'll use for mat leave) then seperate car savings accounts, for tax, insurance, MOT, maintenance etc as one of our cars costs more than the other- why should one of us choose an economical car and then have to contribute to the one who chose a sports car- that's the reasoning not that one has a sports car, but it gives us autonomy over what car we can choose, within reason. And then seperate 'spends' clothes, meals out, drinks with friends, our mobiles, make up eyc as we both have different priorities for example I'd never pay £40 a month for a phone, he'd never pay £25 for moisturise. Doing it this way save a ton of arguments over what we each spend money on and we can treat each other to meals out and presents if we want and it ensures all bills get paid.
Now to the point. I've bought 90% of baby stuff for baby due in 3 weeks. This is because OH has been a student for the last year and has only been able to pay household bills and petrol for himself plus a few spends- I've been working full time so have more money. He's now got a job so has bought a few things.
I think we should have bought it all jointly but due to his finiancial situation it just wasn't possible. That's fine, sometimes you have 'to take one for the team' however if I'd known he had money just sitting there I'd have just said 'you owe me x amount for the car seat I just bought' and he'd have happily given it me (as long as we'd discussed the item as being necessary/ useless wanted before hand).
How each couple chooses to dish out money is up to them- I'd hate to be paying less than 50% of household bills, regardless of the difference between mine and OHs pay, it's just the way I am. However when it comes to kids I believe each parent should contribute 50% as well, to everything.