Three-month-old babies without calcium deficiency generally do not need special calcium supplementation, such as calcium deficiency can be strengthened through breastfeeding or formula feeding, vitamin D supplementation, if necessary, the application of calcium gluconate and other calcium supplements. Babies in three months generally breastfeeding or formula feeding can meet the baby’s demand for calcium, do not need to calcium supplementation. However, for babies with calcium deficiency, calcium deficiency can be corrected by strengthening breastfeeding or formula feeding, getting more sunlight, applying vitamin D drops to enhance calcium absorption, and applying calcium gluconate and other calcium supplements when necessary. When the baby has night terrors, excessive sweating and other symptoms of rickets, it should go to the hospital in a timely manner, and under the guidance of the doctor to improve the examination, follow the doctor’s instructions for treatment, and pay attention to ensure that the baby’s life is fed adequately. All of the above drugs should be used under the guidance of a doctor.