If a baby has phlegm in the throat, it may be due to congenital laryngospasm, which often resolves itself by the age of 2-3 years. However, it is important to prevent colds and shocks to avoid exacerbating symptoms.
If a one-month-old baby feels phlegm after drinking milk, it may be due to a respiratory infection or congenital laryngospasm. The former requires treatment, while the latter usually heals on its own.