New research published today has suggested that the rise in the number of children with autism may be due to doctors better recognising the condition.
The number of children with autism rose dramatically in the 1980s and early 1990s, however the numbers have now levelled off.
This means that the controversial MMR vaccine is probably not linked to the increase as has been suggested.
Figures from a study led by Professor Brent Taylor at the Royal Free Hospital found that the number of children being diagnosed with autism peaked in 1992 after increasing rapidly year by year from 1979. If autism was linked to MMR the numbers should have jumped sharply after the vaccine was introduced in 1988.
However they also found that parents are more likely to associate MMR with autism than they were before a controversial piece of research linked them in 1997, whatever findings are made now.
The National Autistic Society welcomed the study, explaining that it is difficult to get accurate figures on the incidence of autism.
Stuart Notholt, director of policy for the charity told the BBC: 'Data on the numbers affected by autistic spectrum disorders continue to be sparse and it has been difficult to compare current numbers with figures from earlier years.'