It didn't fall out the other times?
Mine falls out in clumps right on the 3 month mark - I have a lot, anyway, but it seems to like falling out at my temples, in particular, which is annoying! It'll start growing back - it's just the hair that didn't shed while you were preggers I've been contemplating shearing mine off again, in anticipation of the great shedding. I've been growing it for about a year, though, even though every couple of months I nearly call my hairdresser to cut it all off again...it'll look better short and thin than long and thin, and when it grows out it grows corkscrew tight, so maybe it's better off super short again!
Folding flannel flats tonight, ready to stack into the bookcase, just in case my GF forgets to bring me her MCNs...