There are few issues that preoccupy new parents more than this : Is my baby growing normally ? When the percentiles seem off-kilter , we worry -- but experts say there 's rarely reason for concern . A growth chart can be used to monitor where a child 's height and weight falls in relation to national averages . For starters , healthy kids come in a wide range of shapes and sizes , and they do n't grow at a steady rate , either . Your child can look very different from your friends ' kids -- or from his own siblings at the same age -- and still be completely normal . What influences growth . At birth : A baby 's size when he 's born is based partly on genetics . Firstborns tend to be smaller than subsequent children because the uterus is smaller and tighter in first-time moms . Boys are larger than girls , and multiples , boys and girls , are smaller than average . Some environmental factors that can influence a newborn 's size : . • the mother 's weight -- very heavy women tend to have larger babies . • weight gain during pregnancy -- a very low gain ( under ten pounds ) usually means a smaller baby . • whether or not Mom smokes or drinks a lot of caffeine -- both of which can limit an unborn baby 's growth . • a mom 's chronic illness -- diabetics , for instance , often have very large babies . During the first two years : A baby 's growth is based on a combination of her birth size and the size she 's genetically programmed to be : A small newborn who 's going to be a big child will grow faster in the first two years than a big baby who 's going to be a small child . Parenting.com : Baby milestones . Laura Hileman 's son , John , was 23 inches long when he was born -- the average newborn is just 20 inches -- and his pediatrician joked that he might be seven feet tall as an adult . `` But based on my height and my husband 's , the doctor did n't think that would happen , '' says the Nashville mom . Sure enough , by the time John was 3 , his growth had slowed and his height was just average for his age . Parenting.com : Toddler milestones . During childhood : Both weight gain and increases in height come in short bursts of what can seem like rapid growth -- which is why kids can sometimes look almost chubby one month but lean the next . The duration of a growth spurt , as well as how much a child grows during one , differs from child to child ( and from spurt to spurt in the same child ) . But it 's not uncommon to see a visible difference in a very short time : At age 10 , my son Sam once outgrew a pair of dress pants in less than a week . No one knows what causes a kid to shoot up one month and not another , but there does seem to be a seasonal pattern . `` Although we do n't have a good explanation for it , children seem to grow fastest in the summer and slowest in the fall , '' says Joseph Gigante , M.D. , associate professor of pediatrics at Vanderbilt Children 's Hospital in Nashville . Doctors do know what triggers growth in the first place : It 's the human growth hormone , a chemical produced in bursts throughout the day but released largely during sleep . That 's why it 's important for kids to get the shut-eye they need throughout childhood and adolescence . During puberty : After infancy , the tween and teen years are the period of most rapid change . For girls , the growth spurt begins between 10 and 11 and lasts until around 15 ; for boys , it starts about two years later and lasts until age 17 or so . Girls typically stop growing about three years after they 've had their first period , but boys continue to grow throughout their teens . Parenting.com : Ages , stages hot spots . Ways to keep track . Until 2002 , the growth chart -- the tool doctors use to make sure kids are growing normally -- was based exclusively on norms for bottle-fed Caucasian children . Since breastfed babies tend to be smaller , as do Hispanic and Asian-American babies , the chart now includes averages for all ethnic groups , as well as for breastfed infants . In addition , the new charts track body mass index , which helps pediatricians know when a child is at risk of obesity . Parenting.com : Guide to childhood obesity . Most growth disorders are diagnosed by pediatricians , not parents , but sometimes a child who is n't growing normally can slip through the cracks . According to a study in the Archives of Disease in Childhood , about 70 percent of all kids are measured inaccurately at their checkups . ( Measurements tend to be off by about half an inch . ) So watch carefully as your child is being measured . And feel free to pitch in , if needed , to hold a wiggly baby still , which will help make sure the measurement is accurate . Double-check to see if the nurse records this information on the correct chart for your child 's age and sex , too . My son Sam was once briefly in the 110th percentile for height ; then the nurse realized she 'd charted him on the curve for girls , not boys . Parenting.com : Height calculator . By comparing your child 's current place on the chart with earlier recordings , your doctor will be able to see if he 's growing normally . Signs that something may be amiss : . • His height seems off , given the height of his parents or siblings . • He 's nowhere near the averages . • He drops 20 percentile points or more from one year to the next . • He 's gaining weight much more rapidly than he 's gaining height . • Puberty comes very early or very late . In such cases , your doctor may suggest a specialist . Most of the time , though , you just need to wait for the next growth spurt . And then you , like me , may find yourself buying your child another new pair of dress-up pants . E-mail to a friend . Try a FREE TRIAL issue of Parenting Magazine - CLICK HERE ! Copyright 2009 The Parenting Group . All rights reserved . Reproduction in whole or in part without permission is prohibited . Margaret Renkl is a contributing editor to Parenting and the mom of three kids .
Use a growth chart to see where your child falls among average children . Children seem to grow fastest in the summer and slowest in the fall . Very heavy women tend to have larger babies . Comment: