thanks for your query at HCM
rattling sound while breathing is called wheezing
Recurrent coughing and wheezing occurs in 35% of preschool-aged children. Of these, approximately one third continue to have persistent asthma
into later childhood, and approximately two thirds improve on their own through their teen years. Asthma severity by the ages of 7-10 yr of age is predictive of asthma persistence in adulthood. Children with moderate to severe asthma
and with lower lung function measures are likely to have persistent asthma as adults. Children with milder asthma and normal lung function are likely to improve over time, with some becoming periodically asthmatic (disease-free for months to years); however, complete remission for 5 yr in childhood is uncommon.
hope this will help you