Development standards for seven-month-old babies: The height of a seven-month-old baby is generally between 66.7 cm and 73.3 cm, and the weight is between 7.9 kg and 10.2 kg. In terms of motor ability, a seven-month-old baby can already support his body and sit up. He also likes to grasp small objects with his fingers. He will try to hold a spoon by himself when eating.