Nine-month-old baby\’s height and weight standard chart The baby\’s height and weight is one of the important indicators to understand their healthy growth. For nine-month-old babies, as their bodies continue to grow and develop, their height and weight will also change. Understanding the nine-month-old baby\’s height and weight standard chart can help parents better understand the baby\’s health and growth. The height standard chart of a baby is generally related to his or her weight development. The height standard chart can help parents understand whether the height of a nine-month-old baby is within the normal range.