Most child characteristics—including weight and height—vary across a wide range. View any group of children of the same age and gender, and you will see some children who are shorter than others, some who tower over their peers, some who seem scrawny and some who appear to be carrying extra pounds. Doctors and parents have an interest in tracking a child's height and weight over time to determine if the child is developing normally and to monitor for possible health problems. The normal weight and height for a 4-year-old will include a spectrum of sizes and shapes.
Doctors use growth charts to evaluate a child's weight and height status. Growth charts show the range of heights and weights for children of different ages and genders. Doctors routinely weigh and measure the height of children and then identify the child's percentile placement on the growth chart relative to other children of the same age and sex. The higher the percentile, the taller or heavier the child is compared to her same age and sex peers. A child in the 95th percentile in weight weighs more than 95 percent of the children of the same age and gender. Children are generally considered to be within the normal range if their height and weight is within the fifth and 95th percentile.
Normal Height and Weight
Normal height and weight can be estimated using the fifth to 95th percentile rankings from growth charts, such as found at KidsGrowth.com. The normal weight for a 4-year-old boy or girl is from 27 to 50 pounds. The normal height for a 4-year-old boy or girl is from 37 to 46 inches. A child that is higher or lower than the normal range in height or weight is not necessarily unhealthy. Children differ in stature. Some are shorter and weigh less, and others are taller and weigh more.
Rate of Change
A child's percentile ranking in height or weight at any particular age is not the most important indicator of potential health problems. Rather, relatively sudden changes in a child's pattern of growth might signal problems. Children grow, so doctors expect that their weight and height will increase over time. However, doctors might express concern when a child's percentile ranking changes dramatically from one year to the next. A 3-year-old who slips from to the 70th from the 40th percentile in height by the time she reaches age 4 might have a growth problem.
Potential Health Problems
Children might have health problems if they show a large discrepancy between their percentile ranking in height and weight, according to Kid's Health. A 4-year-old in the 80th percentile in weight but 30th percentile in height is overweight. Another possible problem is signaled when a child's rate of growth in weight doesn't match his rate of growth in height, or vice versa. For example, a 4-year-old who rises or falls precipitously in weight relative to his height over the course of a year is showing a rapid weight gain or loss, which might reflect metabolic or other problems.
Causes of Small or Large Stature
Four-year-olds might be low or high in height or weight because of familial, constitutional, congenital, hormonal or nutritional reasons. Four-year-olds who have especially small or large parents will likely be similar to their parents in stature. Some children have a constitutional growth delay. They start out average in size but have slower than normal growth during infancy and childhood. These 4-year-olds usually will have a growth spurt in adolescence and catch up to the average. Some small 4-year-olds might have congenital conditions such as Down's syndrome, a congenital infection such as herpes, or they might have been exposed prenatally to alcohol, toxins or smoke that inhibited their in utero and post-natal growth. Hormonal or nutritional syndromes can also contribute to either small or big stature.