BronchiolitisThis infection of the lung's smallest passages, usually caused by the respiratory syncytial virus (RSV), produces rapid, shallow breathing.
Peak age: 4 to 7 months.
What to do: Give fluids, make sure the house isn't too dry, or use a cool-mist humidifier in her bedroom. Watch symptoms carefully: Most cases get better in a few days, but about 125,000 infants under 1 are hospitalized each year to receive fluids or oxygen. Serious cases can also increase the risk of asthma. If your child's coldlike symptoms rapidly worsen and her breathing becomes faster and labored, seek emergency medical help.