The symptoms of a cold in a baby over 40 days old are definitely different from those in adults. Parents should observe whether the baby's behavior has changed. For example, if the baby becomes noticeably fussy or irritable, especially while sleeping, or if the baby has nasal congestion, a runny nose, or sneezing, these could be signs. Also, if the baby drools bubbles at the corners of the mouth while sleeping quietly, breathes noticeably faster, vomits milk after feeding more frequently than usual, or if there is an increase in the frequency and looseness of stools and bloating, these may indicate a cold. If cold symptoms appear, please seek medical attention promptly, as babies have weaker immune systems and their conditions can progress quickly. Without timely intervention, it is easy for the condition to develop into pneumonia.