Irregular breathing, noisy breathing or rattling in your baby’s chest are normal and are most often caused by nasal or upper airway mucous (see Nose congestion). Healthy babies may have irregular breathing for the first several months of life. They may have periods of regular breathing interrupted by brief a brief period (5 - 10 seconds) of no breathing (apnea). A breathing problem in the chest itself, however, would also cause other symptoms. Contact your provider right away if you notice: