2-year-old baby bone strength insufficient may be related to calcium deficiency, lack of vitamin D, lack of vitamin A and so on. 1. Calcium deficiency: calcium for the growth and development of human bones has a very important role, due to the 2-year-old baby is in the period of growth and development, the body absorbs calcium less than the amount of calcium needed by the body, may lead to the baby calcium deficiency. When the baby lack of calcium, it may lead to the baby’s bone strength is not enough. 2. Lack of vitamin D: Vitamin D not only promotes the body’s absorption of calcium, but also promotes bone growth. Due to the lack of sun exposure time or insufficient intake of vitamin D in the baby’s diet, there is a possibility of vitamin D deficiency, which can lead to insufficient bone strength in 2-year-old babies. 3. Lack of vitamin A: Vitamin A plays a very important regulatory role in the process of cell growth, differentiation, proliferation and apoptosis, including skeletal tissue, nervous system and cardiovascular system. Lack of vitamin A will make the baby growth stagnation, developmental delay, skeletal dysplasia, etc., which will lead to the baby bone strength deficiency. When a 2-year-old baby has insufficient bone strength, he or she should seek medical attention in time to clarify the cause and treatment under the guidance of the doctor.