What causes congenital torticollis in newborns?

Congenital torticollis in newborns is generally considered to be related to multiple factors. First, intrauterine mechanical forces play a role: when the fetal position in the uterus is abnormal, particularly in breech presentation, significant pressure can lead to structural changes in the neck. If there is a hematoma in the sternocleidomastoid muscle, it may result in a palpable mass within this muscle, followed by gradual absorption of the hematoma. Additionally, venous return problems may occur; during breech delivery, failure of the fetus to enter the pelvic cavity can cause venous obstruction, leading to ischemia, edema, and fibrosis of the sternocleidomastoid muscle.