Since we are observing that baby start crying immediately after birth. Fortunately that crying is the indicator that the baby is born with no abnormality scientifically that crying is very important. If the baby doesn't cry then it means that there is infection or any other abnormality in the newly born baby. So it's a red signal to show it to the doctor. Now we're coming to know the scientific reason behind this. So ,
When the baby is in the utreus he or she takes breath (oxygen) through mother's placenta ( connection between mother and baby) but when he comes outside of mother now his alveoli has to open to adopt itself to take oxygen directly from the air so relaxation takes place which producing dolor(pain) in the newly born baby's body therefore he is crying.
But when he is not crying it means that the alveoli ( lungs) are not preparing itself to take oxygen directly from the air so baby is not crying but it can lead to the death of the baby.
And another reason behind this crying is the temperature 🌡️🌡️ difference between the mother's body and the environment. So if baby is not crying it means that the baby's sense is not activated.