Young children thought to have special educational needs and disabilities (SEND) could instead be suffering from trauma and Covid issues.
Headteachers in Bristol said a lack of social interaction during lockdown, or traumatic events, might be causing issues similar to autism.
However, with a "nurturing approach", they could get back on track.
The comments come as demand for SEND support in early years education is rapidly increasing in the city.
Headteachers told a schools forum at Bristol City Council that restrictions from the pandemic have created a vast range of problems, according to the Local Democracy Reporting Service.
Lockdown meant that some children have never met health visitors and had a lack of social interaction during their early years.
Simon Holmes, headteacher of St Philip's Marsh Nursery School, said: "Children's behaviour that's seen as SEND is possibly due to trauma, it's really hard to unpick."
