When you take your 1-year-old in for a well-child exam, your pediatrician will first get an overall impression of his health. Is he alert and bright-eyed? Does he display curiosity and an interest in the doctor and the examination procedure? Next the doctor will weigh and measure your child and chart his height and weight on a graph that displays his growth in terms of percentiles. This is a way of comparing your child with others of the same age and gender. If your son's height is at the 75th percentile, for instance, it means that he is as tall as or taller than 75 percent of the boys in his age group.
It is important to remember that normal height and weight encompass a wide range. Your child's weight at 1 year is likely to be approximately three times her birth weight; by the end of this year, her birth weight should have quadrupled. As for height, girls generally double their birth height at around 19 months; it takes boys approximately 6 months longer.
Pediatricians are often asked to predict at age 1 or 2 what a child's adult height will be. Some still rely on the formula that adult height will be approximately twice the child's height at the end of the second year. Others, calling this a popular bit of folk wisdom, believe there are too many variables involved to make a definite prediction. Generally, a child's eventual height can be predicted by the average of his two biological parents. There are exceptions, so don't worry even if your child is much smaller or larger than average.