Not all issues become obvious as soon as the infant is born. In some cases, children start showing symptoms throughout the first years of their life. At that point, the pediatrician might order some tests that might uncover the injury.
Other cases result in the immediate diagnosis of the injury as soon as the infant is born. The Apgar score might be the first place to detect the presence of an injury. Other tests, such as an MRI or a CT scan may reveal whether the baby has sustained an injury at birth. The doctor would inform the parents at that point how severe the condition is.