Body Mass Index (BMI). Body Mass Index (BMI) is measure of body fat based on height and weight that applies to both adult men and women. BMI does not differentiate between body fat and muscle mass. Therefore, body builders and people who have a lot of muscle bulk will have a high BMI but are not overweight or obese.
The bump: or hematoma as we call it, can last for 1-2 weeks. Sometimes it gets slightly worse before it gets better. If the child is acting normally, and not vomiting uncontrollably, she should be fine. If she starts doing those things, call your pediatrician.
Time Frame. Baby acne, while sometimes visible at birth, usually does not become evident until two to three weeks after delivery. Parents often confuse small bumps present on a newborn's face at birth, called milia, as baby acne, but milia will disappear within a few weeks, while baby acne persists.