Low height of four-month-old infants is usually caused by bad lifestyle habits, calcium deficiency, growth hormone abnormality, etc. It is recommended to adjust lifestyle habits, take calcium supplements, use human growth hormone and other treatments. 1. Bad habits: If a four-month-old baby drinks less milk, or sleeps for a short period of time at night, or has poor sleep quality, etc., which may lead to low height, it is usually recommended to adjust the lifestyle, for example, feeding the baby a small amount of times, and ensuring that the baby sleeps at night and has good sleep quality. 2. Calcium deficiency: Calcium deficiency can also lead to low height in four-month-old infants, and it is usually recommended to take calcium lactate granules and vitamin D to supplement calcium as prescribed by the doctor. 3. Growth hormone deficiency: four-month-old infants with low height may also be due to growth hormone deficiency, eligible for treatment with growth hormone and other drugs as prescribed by the doctor. Four-month-old infants with low height may also have other causes, such as hypothyroidism, etc., it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, and then give targeted treatment or treatment.