A new baby brings turbulence to a home, no matter how organised. You may have a straightforward delivery from which you recover in mere hours, or you might have a section or post-partum haemorrhage that lays you out for weeks.
Almost every new mother needs plenty of rest in at least the first few days. A lot of ironing can mount up in that time, and dust and washing up and and and and... I was absolutely astonished by how completely exhausted I was in the first few days, and how little I could do in that time that I had previously considered not difficult or strenuous or timeconsuming in the least.
If it's normal for you to do all the housework, you need to be prepared to let the house get messier than usual or get someone else (family, friend or employee) to do some jobs in the first days or weeks.
Most women are back to something approaching normal physical fitness by six weeks or so. What stops most of them from doing their previously normal housework is the small person - either by keeping you up all night so you're tired, or by doubling your laundry burden, or by refusing to be put down, or being so squidgey and delicious that you want to stare at them all day.
It isn't impossible to keep a clean house after a baby, particularly if you start from a good foundation (eg having places to put things away, good laundry facilities, surfaces that are easily cleaned), but you are underestimating how much your life will change.
My top tips: prioritise (and your priorities will be different from mine but I prioritise bathroom and kitchen and laundry over dusting and hoovering, for example) and get a sling. If your baby needs to be upright, eg for reflux, or likes to be held a lot, you can sling and get on with it.