This was my thought as well. I’m likely on the spectrum (as I have learned recently, because of my kids) and I would consider myself hypersensitive. To a variety of sensory inputs - noise, smell, touch, heat, cold, tickling and probably also pain. The latter being hard to quantify of course.

But I could certainly imagine that a mother with autistic traits could be someone who takes painkillers more often than the average person.

That’s very interesting! I’ve been sleuthing for personal reasons and I’ve recently arrived at the central nervous system element called the nucleus of the solitary tract (NTS), which integrates sensory processes including pain reception. I’m tracing a particular activator of the mineralocorticoid receptors for which NTS has special relevance, but the end target overall seems to be mTOR in the NTS, which isn’t so niche and is studied in autism.

It seems that higher sensitivity to pain could be a very plausible cause. I believe there's studies showing lowered (and altered) pain tolerance with autism.

Though I'd expect that if aspirin did have an affect that it'd change the prevalence or severity of autism in children having genes related to autism.

There'd be a first order correction fornthe likelihood that aspirin is causitive by controlling for increased ibuprofen and tylonol usage as well. The second order correction would be whether autistic people were more likely to use aspirin over ibuprofen or tylonol, etc.