The Bumbo is to help babies sit upright. The company claims the seat stabilizes the child into slight hip flexion which facilitates lumbar extension and many other claims.
If you take a closer look at a baby in the bumbo you will see it does the opposite. It puts the baby's pelvis in a posterior tilt which facilitates lumbar flexion that ends up putting the baby's chest behind their pelvis and then the head has to come too far forward to compensate. Mary Weck, clinical coordinator physical therapy at Children's Hospital in Chicago addresses these claims.
Babies rely on different positions to promote activation of their muscle groups and joint movement to achieve trunk control or pelvic stability. The bumbo locks the child in one position so this cannot occur as well as places the legs at a higher angle than the pelvis so no natural weightbearing can occur.
Babies rely on different developmental positions to learn about shift of weight, develop strength, and organization so they can go through all the developmental movements from lifting the head, to rolling, to crawling, sitting then standing. We are doing babies a disservice when we interfere with their natural progression of development.
