I think you have to do calculations the whole time when making decisions about family maybe that is where people are going wrong
When we were planning our first baby, our calculations amounted to working out how much we would have to save before / during pregnancy so that we’d still effectively have my full salary (even though I’d be on maternity leave) for a full year.
Then, during that 1st year given that nature had decided to throw a spanner in the works and give us twins
the next calculation was how we could work my return to work (and whether that would be full time / part time etc) and what the childcare costs would be.
Then, when the broodiness kicked in again, we did a whole lot more calculations – we had a much better understanding of the likely costs of children so we thought about whether we could afford to extend the house, a new car, more maternity leave, childcare costs for another baby for 3 or 4 years (even working out if Number 3 turned out to be Numbers 3 and 4!). on top of nursery fees for the other 2 / after school depending on how long it took to get pregnant again. If we hadn’t had been able to afford it, we wouldn’t have had Number 3, even though I desperately wanted another.
As a pp said, its not the equipment / food etc that is expensive, it’s the maternity leave & childcare. I was lucky in that I got half pay rather than statutory maternity pay, but even then, a year of maternity leave “cost” me at least £25k gross. Then when you go back to work, just one child’s nursery fees were £1200 a month when DD left in 2013, and after school for 2 children (the twins) was £25 a day, breakfast club (if we needed it) is £15. So if I’d have gone back full time, our childcare bill would have been over £2k a month (term time) and then we’d have to pay for holiday cover on top.
Its those sorts of expenses that come as a shock and you really need to give some thought to.