...perhaps, but let me start with my disclaimer:
While having an intellectual discussion on the value of vaccines, I discovered some charts and information on the net that proposed that autism was on the increase. Before I go any further, let me quickly assure you that the rumour of a link between vaccines and autism does not have a leg to stand on for a number of reasons, including that the experts believe that there is no link, the most notorious quacks (Mercola & co.) say there is a link, and even after vaccine manufacturers removed the scary ingredient, thiomersal, which the quacks believed was causing the autism (and the experts didn't), the quacks continue to spread these rumours.
So, onto the topic at hand: If vaccines weren't causing autism to be more prevalent, what was? Could it be that something else had changed over the last 25 years? No, not possible, because nothing has changed at all. Everything is exactly the same as it was 25 years ago... we still listen to records, have three television channels and phone people using a funny dialling device that requires sticking your finger in a hole and rotating it clockwise six times.
But seriously though, I recently discovered this study from the peer reviewed journal, Psychological Medicine, published by Cambridge University Press in 2014. I would recommend taking a peek, not reading the entire thing, but just enough to get an idea of the kind of detail, thought and expertise went into the study. I have to admit that I can't understand a lot of what they're saying, either because I've forgotten a lot of what I learned in a year of statistics lessons or because my classes were not advanced enough.
Anyway, the gist of the extensive study is this: "...there was no clear evidence of a change in prevalence for autistic disorder or other ASDs between 1990 and 2010."
Also of interest is this: "These results support research findings (Fombonne, 2008) that suggest that early childhood factors, for instance vaccinations, have had no observable effect on the occurrence of ASDs. However, there is some evidence that in-utero stressors (such as maternal stress, obesity and pesticide exposure), birth complications and advanced parental age may be associated with higher risk of ASDs (Scott et al. 2013)."