OP,

If this is recent/new maybe it's something related to the inner ear?

My kid has DCD but has pretty much always been clumsy since he could walk and falls fairly frequently.

My Aspie didn't fall but he certainly has had an unusual gait his entire life.

Yes! My child did this till at least age 3 and maybe later, but it did stop. Even in his walking in the early years, he didn't have a solid step. My friend said my son sort of "skittled" even though it was a fairly normal gait. My only guess is that it has something to do with the brain's attention to the task of walking and that sometimes it stops sending signals to keep doing what it's doing, like walking, and the legs just give out. This is my best guess. Or similarly it could be a stamina or tone thing where the posture is held up by weaker core muscles that have to work a lot harder to keep the body up and sometimes it just gives way. I know exactly the kind of collapsing you are talking about. My son actually got a few mouth injuries because of falls where he maybe didn't get his hands out fast enough (may be another issue) to break the fall. But that stopped in preschool. I do see some evidence of difficulty sustaining attention on body movements (e.g. yoga positions are very difficult to hold and in general coordination is poor, poor posture--he's a sloucher--like me! and I can identify with the stamina giving out). But the falls stopped. I don't remember a progression of falls getting worse per se. For your DD it might be that other milestones are being hit and often this leaves other skills behind temporarily. But you might consider having an OT or PT consult on core strengthening exercises you can do. I'm guessing heelbarrow walking, sitting on an exercise ball when doing activities at a preschool sized table, yoga, horseback riding, ballet type dance lessons might help.

Even though my daughter was diagnosed three years ago, I'm still figuring things out about ASD. An endless mystery.

My daughter, age 4.5, has been falling down frequently. Like we will be walking, then suddenly she'll fall -- not trip, but fall as if her knees gave out on her or something. Happens a few times every week at least, and seems to be getting a bit worse (whereas other gross motor stuff has been getting better).

I'll add this to my list of questions for our developmental pediatrician and OT, but, in the meanwhile, does anyone have a coherent explanation of what's going on?

And, for those who've been around the block, does this get better? How?

Thanks.