I know it is normal that as breastfed babies get older they will gradually poop less. Over the past week or so, my little guy has gone from making about the same number of diapers as he gets feedings, to only a few times per day. Yesterday he only made three BMs and so far today he's only had one. It just seems like the change happened really fast! Does that sound normal for his age? He's 6 weeks today.
He seems okay otherwise, not constantly hungry or anything, so I think he is getting enough.
Re: Decreasing bowel movements?
I was thinking growth spurt, too, although some healthy BF babies don't even poop every day. My LO ranges from every 2-3 days to pooping at every feeding. Like PP said, quantity-wise it's still about the same.
But when she's in a growth spurt, she definitely poops less.