Infants do not grow hair, may be due to the growth and development time, but also may be due to the lack of trace elements or vitamins, bacterial or fungal infections, endocrine diseases or genetic metabolic diseases. 1. Infants enter the stable hair growth period only after half a year old, the growth rate of each region of the skull and brain is different, sometimes visible hair thinning distribution is different, but with age, the symptom will gradually disappear. 2. Lack of trace elements or vitamins: Slow hair growth is caused by trace elements such as zinc, iron, and vitamins A and D. The hair growth rate of infants can be reduced due to the lack of trace elements such as zinc and iron. It is important to add supplemental food in time to ensure balanced nutrition for infants. 3. Bacterial or fungal infections in the scalp cause damage to the hair follicles, resulting in slow hair growth. 4. Endocrine and genetic metabolic diseases such as hypothyroidism and phenylketonuria may also affect hair growth. In addition, a very small number of infants suffer from lead poisoning, electromagnetic radiation and other environmental problems and hair thinning and yellowing. Therefore, when parents are faced with infants who do not grow hair, they should identify the cause of the problem, seek timely medical attention and take active treatment.