A head circumference that is the same from three months to six months is not normal and is usually associated with microcephaly, malnutrition or calcium deficiency, and requires early medical attention to avoid delays. A child’s head circumference is about 33-34 centimeters at birth, averaging about 40 centimeters at three months and 42 centimeters at six months. If a child’s head circumference does not increase from three months to six months, most of the growth and development is abnormal, and need to consult a doctor for examination, often the earlier the intervention the better. If it is caused by congenital microcephaly, most of them are related to heredity, infection and other factors, and need to follow the doctor’s advice to give surgical treatment, rehabilitation training and other treatments; if it is caused by malnutrition, parents need to strengthen the breastfeeding care, advocate breastfeeding, regular follow-up of the baby’s development, and comply with the doctor’s advice to be dietary interventions. Due to the measurement error, parents are advised to measure in the same physician, do not blindly give children medication, need to consult a doctor in a timely manner, under the guidance of the doctor to improve the cranial MRI and other related examinations, and follow the doctor’s instructions to be targeted treatment.