As physical therapists working with infants, we spend lots of time talking to parents about ways to help their infants develop their strength, balance, coordination, and motor skills. One of the questions that we often hear is whether parents should use a Bumbo seat to help an infant learn to sit up. When we think about it, it is no wonder why parents ask this question so often. Step into your local baby store, read a parent’s page on facebook, or chat with friends with young babies and you are likely to hear some reference to the bumbo seat. There are few seats out there quite like the bumbo in it’s shape and design, and the marketing for it is widespread and effective. Images of infants in the bumbo show babies happily sitting up and sometimes even playing in these seats.
Unfortunately, when we look at the design of the Bumbo seat, there are some features of the seat that make this a less than perfect choice for helping your baby learn to sit. To illustrate this, it is important to understand that a baby learns to sit up by using the muscles on the back (extensors) and the front (flexors) of his body together. When a baby is learning to sit up, her bottom (pelvis) should be the farthest thing back, and her shoulders should be in front of her hips. This position places the pelvis in a slight anterior tilt, with the trunk flexed forward over the legs. You can picture this as your baby folded over and eating his toes if you are not helping to support his trunk. As he becomes stronger, your baby will begin to use his back and hip extensors to move into a more upright position and stay up in sitting.
When a child is positioned in the bumbo seat, the rounded bottom and back of the chair places her pelvis in a posterior tilt with her bottom tucked under her, limiting the ability of the trunk and hip extensors to be active. Adding to this position, the front of the seat is elevated under the legs, making it tip them back even more. This positioning of the pelvis is a large part of the reason that infants look slumped over when sitting in the Bumbo. Without having the space or positioning to lean forward, you baby is not encouraged to turn on her extensor muscles and stay in a more upright position. When the body is in this rounded and slumped position, the head moves too far forward over her trunk, leading to additional problems with your baby’s posture.
Aside from the major concerns about a baby’s posture in the Bumbo seat, it is also important to think back to your baby’s primary motor goal during his first year: learning to move. Each month, we think about our baby achieving new motor milestones. All of these skills build on each other and within each one of them, your baby is doing thousands of repetitions of trial and error before she masters a new skill. If we simply place her in a seat that confines her movement and holds her in a position, it is much more difficult to fine tune how to handle her body in order to master the skill independently. If your child needs to be in a seat like the Bumbo in order to be upright, he likely does not have the strength, coordination, or balance that he requires to be able to sit independently. To help him progress with his motor skills, your baby would likely benefit a great deal more from play time that encourages him to strengthen his muscles and allows him to freely explore his environment. Tummy time, back play on the floor, rolling, and even supported sitting with you, in ideal alignment, can be extremely beneficial to helping your baby master sitting on his own.
Like adults, babies need to move and change position frequently. Once they can sit, infants rarely spend prolonged periods of time sitting still without actively reaching, shifting their weight from side to side, moving to their tummy or back to get a toy, or otherwise wiggling and shimmying around. As they do this, they are learning about their environment and developing the processing of the vestibular system. This system helps tell the brain where a person is in space and gives information about how the person is moving. Spending long periods of time contained in any device, including the Bumbo seat, can limit your baby’s opportunities to provide this important sensory information to the brain and help develop this sensory system.
As you look towards helping your baby master sitting up on his own, remember that a strong foundation for movement comes from developing strong muscles, balance, and coordination and exposure to a variety of positions. Spend time playing with your baby on her back and belly, help her play on her side and learn to roll, and offer her the experience of sitting and standing up in good alignment. With a strong foundation, you will be excited to see how your baby can learn to sit on his own and will be on the way to his next milestone.