cephalohematoma

https://learnmoreaboutnest.birchreport.com/posts/understanding-birth-injuries-learn-more-about-cephalohematoma

Cephalohematoma is a soft, puffy swelling on a newborn's head caused by blood collecting between the skull bone and its outer covering. It usually appears within hours after birth, often from the pressure of a prolonged or instrument-assisted delivery. While it can be alarming for new parents, the bump typically resolves on its own over weeks to months without any lasting harm.