DS lost a lot of words between 7 mos and about 20 mos. Like all of them. Clear regression etc. we got sent to an SLP despite our protestations. It turned out, as far as can be worked out, that his language skills were just so far ahead of his articulation that he was getting frustrated enough to give up completely.
When he had his 6 mo followup with the SLP, they went from wanting to treat him for SELD to wanting to treat him _as though he were twice his age_ for articulation problems. We declined. Damned asynchrony.
It seems that good receptive language is a very important marker for persistent problems. If yours has good receptive language, don't worry till she's over 2.
-Mich
