Swollen eyes of 20-day-old babies may be caused by poor sleep quality, nephrotic syndrome and conjunctivitis. 1. Poor sleep quality: 20-day-old infants who always lie on their sides are prone to edema in the area near the bed. This situation can be improved by adjusting the infant’s position. 2. Nephrotic syndrome: 20 days old infants suffer from congenital nephrotic syndrome, the decline in renal function leads to poor fluid metabolism, which is prone to the symptoms of swollen eyes. 3. Conjunctivitis: Parents do not pay attention to the baby’s eye hygiene, resulting in 20-day-old babies with bacterial infection of the eye, causing conjunctivitis, swelling of the eyes, red and other symptoms occur. If a 20-day-old baby has swollen eyes, it is recommended to go to the hospital for examination and diagnosis, and follow the doctor’s instructions for standardized treatment.