Normal blood pressure for kids (89-110) may not be high enough. If your child is young, high blood pressure is usually caused by a sedentary lifestyle, which can be changed with some changes in diet and activity. Your doctor will be able to tell you whether your little one’s normal blood pressure is high enough for hypertension. A high reading could indicate that your preschooler is at risk for future hypertension, even though he or she has already had some lifestyle changes and is still within the age for major disease.