Mouth to mouth resuscitation is the act of stimulating or assisting respiration.
Acute respiratory problems
If baby is not breathing and not responding
Only stop mouth-to-mouth when help arrives, or if baby starts breathing independently again.
If it's difficult to blow air in, gently move baby's head to release the airways then try again.
You must start this process as soon as possible.
This advice is only a guide, always consult with trained medical professionals before taking action when possible and when time allows.
From angelababy In Q&A