If a nine-month-old child still cannot sit, it may be cerebral palsy, because a child who cannot sit at nine months of age is obviously developmentally delayed, as a normal child is able to sit more steadily at six months of age. First of all, children with cerebral palsy may have symptoms of cerebral palsy because after cerebral palsy occurs, there will be a significant increase in muscle tone around the body, and at this time, children’s movements are more clumsy and developmental delays, not only may children not be able to sit at nine months, but also at the age of one year, children are often not able to independently walk or stand. Secondly, it may not be a case of cerebral palsy, if the child suffers from congenital hypothyroidism, or trisomy 21 and so on, these causes can also cause the child can not sit at nine months, so the child can not sit at nine months may be a case of cerebral palsy, or it may be caused by other reasons, under the guidance of a professional doctor to identify.