I would love to know the ratios of number of children to household income. I would hypothesise that lower and upper income have more children per household than middle income, be interesting to find out.
Raising children is hard in this day and age, so much expectation on the mother from before the child is even born.
Constant demands to be fit, take the child out every day, entertain the child, keep children quiet in public, feed them all sorts of foods that are not processed, contain little sugar, homemade, breast feeding, baby groups, milestone checks, judgement on parenting style, then get to school and juggling drop off/pick up plus career. Help with/teach child reading, writing, maths homework, attend after-school clubs, swimming, play dates. Making stupid models for primary and providing costumes for the endless 'wow' days/celebrations, cakes for the endless pta events, endless money for 'educational' trips, 11+ prep, sats prep. All this and this is outside of essentials like midwife visits, health care visits, doctors visits/vaccinations, dentist visits, looking after poorly children any hospital appointments. Then there are things that you might actually want to do yourself such as go on trips out or a holiday. Plus all the expenses associated with them.
This is why I laugh when people say that their dogs are like their children...they really aren't and there are plenty of expectations that I have probably have forgotten and omitted and I only got to high school age too.