General two and a half year old baby height is about 92.5cm, so 2 and a half year old height 90cm is slightly lower than the standard value. Babies generally 2-12 years old normal height according to the formula, height = age × 7 + 75cm, that is, 2.5 years old baby height 2.5 × 7 + 75cm = 92.5cm; 3-year-old baby’s normal height is 3 × 7 + 75cm = 96cm. and so on, according to the formula. However, different children, the growth and development rate is not exactly the same, can be based on the above formula according to the calculation, according to the calculated value of a simple judgment, if the baby’s height and the calculated height difference is more, should be timely to the hospital, by the doctor to make professional judgments, and if necessary, the appropriate treatment.