either of two large organs lying within the chest cavity on either side of the heart; they supply the blood with oxygen inhaled from the outside air and dispose of waste carbon dioxide in the exhaled air, as a part of the process known as respiration.
Most babies first pull themselves up to a standing position between about eight months and 10 months. At this stage your baby will need to hang on to you or a solid piece of furniture. By 11 months she may be able to stand on her own.
Confidence votes 30. All babies develop at their own pace. A baby should be able to sit up by themselves between 5 and 7 months. Keep in mind in the beginning they will need some support like pillows stacked around them and as time goes on and muscles strengthen they will be able to do it by themselves. baby should be able to sit up by themselves between 5 and 7 months.