My DS started sleeping through at around 3 months, but then when he got to about 5.5 months it all stopped. For awhile there we were getting up upto 7 or 8 times a night. It's settled back down again over the last couple of months, some nights he sleeps through and some nights he wakes once or twice.

I'd always thought that once they started sleeping through that was it and they would just do it from then on in, but not in our case....