I am up to #4 too, and have found the last 4 weeks harder with each pregnancy. I think mostly because I have had other children to take care of. But I also think my belly has been bigger with each child too - with #3 I felt (and was) enormous - I felt like I was full term at 36 weeks. As it turned out, DD was the size of a full term baby at 36 weeks, as she was 9lb 9oz born! I think that is actually my main little worry this time - that this baby will be even bigger than that!