There is a groove on the baby’s head, the following situations are common: 1, is a normal phenomenon, because the skull itself is made of many cranial bones spliced together, such as the frontal bone, parietal bone, occipital bone, in the process of skull splicing there will be bone seams, gradually disappear with age. 2, vitamin D deficiency rickets, there will be a square skull or saddle head, so that the surrounding cranial bones accumulate so that the skull seams are more obvious, the phenomenon of grooves. After giving vitamin D and calcium supplements, more outdoor activities, sun exposure, and reasonable addition of complementary foods, it will gradually improve and disappear as it grows older.