The briefing from the Parliamentary Office of Science and Technology says children need to be able to co-ordinate and control finger movements to start to write. Most children do not develop these skills until they are at least five.
The report warns: "Forcing handwriting skills upon children before they have the basic co-ordinative powers might be harmful."
British children start school before many of their European peers. Primary schools take children at the beginning of the year in which they become five.
The report cites studies that suggest that an earlier school starting age may have little advantage. Even children who started schol at seven had largely caught up with the earlier starters by the age of nine.
The ability to identify letters by the age of five does not necessarily produce better readers at age 11, and teaching children to read early does not necessarily mean they will be better readers later.
It says: "Studies have found that children with good reading skills generally have access to books at home and parents who encourage their children to read, but do not pressurise them or use systematic formal approaches that are commonly used in schools."
The report was prepared for MPs who are holding an inquiry into early-years education.
The report is available from the Parliamentary Office of Science and Technology or at www.parliament.ukpostreport.htm