Yep, I did it and worse LOL. I was in a 3rd floor unit for nearly 14yrs!
Lets see..... I was TTC, then pregnant with DD1 then TTC and pregnant with twins and had a huge DVT while pregnant. That was a huge struggle and I had to rest going up the stairs.
As a baby I used to carry DD1 in a baby bjorn (or just carry her if I didn't have shopping etc) and keep the proper baby bag in the car and just add to it when I was going out so I didn't need to carry much. I taught DD1 to crawl backwards down the stairs from quite young and she loved crawling up the stairs. With DD2 & DD3 I used capsules when they were babies and took one at a time up or down the stairs a bit at a time. So, I would take one up the stairs a little bit and go back for the other and so on.