At three months of age, normal full-term infants generally hold their head up steadily and are able to support the front half of their body with their elbows when lying prone. Children’s motor development is divided into two categories: gross movements (including balance) and fine movements, and head lifting belongs to balance and gross movements. In general, 1-month-olds try to lift their heads when lying prone; 2-month-olds can lift their heads in the vertical position; 3-month-olds lift their heads more steadily and can support the front half of their bodies with their elbows when lying prone; and 4-month-olds lift their heads steadily enough to sit while holding on to their hands or hipbones. Due to the immaturity of the respiratory system, circulatory system, digestive system and other systems, the motor development of preterm infants is also slower than that of normal full-term infants. To determine whether a preterm baby’s motor development is normal, you should go to a regular hospital, consult a medical professional and follow professional advice.