The charity said that three babies or toddlers a week were hospitalised due to deliberate head injuries in England last year but warned that many injuries were not being recognised.
The issue has gained prominence after it was revealed that a paediatrician failed to spot serious injuries, including a broken spine, to Baby P, two days before the 17-month-old died in August 2007.
The charity said spinal or head injuries often led to lifelong problems including cerebral palsy, learning or behavioural difficulties, or epilepsy.
The guidance has been drawn up by the Welsh Child Protection Systematic Review Group, which includes the NSPCC, the Royal College of Paediatrics and Child Health and the department of child health at Wales College of Medicine, Cardiff University.
Look for less obvious symptoms
Paediatrician Dr Alison Kemp, who leads the group, said: “Signs like swelling of the lower back or bruising to the head or neck are visible injuries. In many cases however, the spinal or head injury may not be immediately apparent so doctors should also look out for less obvious symptoms.
“These could include irritability, poor feeding or excessive crying or impaired neurological function. Inflicted head injuries are the most serious form of physical abuse and are the leading cause of death and disability among children who have been abused.”