Research conducted by charity Ambitious about Autism found that from their child first being referred for an autism assessment, 46 per cent of parents waited longer than 18 months for a formal diagnosis. Some parents reported waiting for more than three years. Children are usually referred by a GP or health visitor for a formal assessment if they suspect the child is autistic. They should then have a multi-disciplinary diagnostic assessment by a team of professionals that can include a paediatrician, a speech and language therapist, and a specialist psychologist. A total of 3,842 parents and carers of autistic children responded to the survey, which was conducted between September and November 2019. Read More.