3 months baby length 55cm more suggest abnormal. In general, 3 months baby length standard, male baby 60.7 ~ 65.3cm, female baby 59.4 ~ 63.8cm, so for 3 months baby length 55cm more suggest abnormal. The baby in the first 3 months after birth length growth faster, about 11 ~ 13cm. if the parents height is low, or intrauterine growth retardation, premature birth, may cause the baby at birth length is low, and after the birth of the milk quantity is insufficient, may also lead to postnatal growth is not ideal, and then cause the 3 months baby length is low. In addition, there is individual variability among babies, even if the length of the birth is low, in the later development of some babies will also have growth catch up, and then gradually reach the normal level. Therefore, for the baby’s temporary low length of the situation, parents should give adequate nutrition, closely observe the baby’s height, weight growth, timely addition of complementary foods, to promote growth and development, and if necessary, pediatric consultation, to clarify the cause of the disease, to take targeted treatment.