A seven-month-old baby who does not sit may be an anomaly and needs to be evaluated by a doctor. For normally developing babies, they will be able to sit alone by the age of 6 months. Babies follow a certain pattern of development, lifting their head at 3 months, rolling over at 4 months, sitting alone at 6 months, crawling at 8 months, and walking at 1 year of age. Most babies follow this pattern, but there are individual differences, and through parental training and enhanced nutrition, they are able to reach the normal level. In addition, it is possible that the baby’s development is delayed, you can test the blood calcium, vitamin D, nervous system, skeletal system and so on. Commonly, rickets caused by vitamin D deficiency may cause seven-month-old babies can not sit. In addition to this, certain babies who are born prematurely, improperly fed, malnourished, or have congenital diseases may also have seven months can’t sit phenomenon. Therefore, if you find that your baby can’t sit at seven months, it is recommended that you go to the children’s hospital in time to find out the cause, and intervene as early as possible if there is any abnormality and treat it as early as possible.