Most major airlines, including carriers like Air India and IndiGo, allow healthy full-term infants to fly as early as 7 to 14 days old. Some airlines technically permit travel for babies as young as 2 to 3 days old, but this usually requires a medical clearance form signed by a pediatrician. Medical professionals generally advise waiting until a baby is at least one to two months old if possible, as their immune systems are still developing and they are more vulnerable to the germs found in recycled airplane air. Additionally, a newborn's lungs are still maturing, and the changing cabin pressure during takeoff and landing can cause significant ear pain. If you must fly with a newborn under one week old, be prepared to provide a hospital discharge summary or birth certificate as proof of age, and always check with your specific carrier, as international regulations can be stricter than domestic ones.