Usually, after the fontanelle closes, the baby’s head shape is basically fixed, and the possibility of changing it again is small, therefore, most children’s fontanelle closes around 1 week old and the head shape is fixed. During this period, there is no need to use any pillow, as long as the baby can avoid sleeping in a fixed position for a long time, so as not to cause head tilt, boat-shaped head or flat head deformity. And after 3 months, with the growth of age, the baby’s skull hardness becomes bigger, the head shape is gradually fixed, but the connection between the skull and the skull is not yet close, and at the same time, with the increasing brain capacity, it still has a certain plasticity, in about 1 week old after the closure of fontanelle, the head shape is basically fixed. In addition, it is recommended that newborns sleep in three sleeping positions: lying down, left and right side lying, so as not to maintain a sleeping position and cause poor bone development of the head.