The resistance of 40-day-old babies is weak, and it is easy to catch a cold, causing nasal congestion. Because the respiratory tract is immature, the nasal cavity is relatively short and small, and the nasal mucosa is tender and rich in blood vessels. Easily stimulated by the outside world, the nasal mucosa is easily congested and swollen, and the secretions in the nasal cavity increase significantly, often manifesting as nasal congestion. To clear the nasal secretions in time, use nasal spray saline, 2-4 sprays per side of the nasal cavity to soften the nasal stool, and use a nasal aspirator to carefully attract out. At the same time, you should feed your baby with water properly, and it is better to use a humidifier or place a few pots of water in the house to increase the humidity of the indoor air. Open the windows frequently to ensure the circulation of fresh air. You can also use a hot towel on the root of the nose. If the symptoms of nasal congestion are not alleviated, go to the hospital for consultation and treatment.