From the moment you brought your new baby home, you’ve been eagerly watching his progress. But what exactly are you watching for, and how do you know if your child is growing and developing properly? This Website will guide you through childhood growth and development as they are measured by the physical and developmental milestones that most children reach at each age level. These milestones include increases in height, weight, and head size, as well as development of cognitive skills (the ability to perceive, think, and remember), motor skills (movement, strength, balance, and coordination), and social and language skills.

A newborn infant is a wonder to behold. It is particularly astonishing to think that this cuddly creature started out in the womb as a microscopic fertilized egg just a few months earlier. Although your infant will undergo tremendous changes during the first year of life, the most rapid and important phase of a child’s physical growth occurs before birth. The detailed “construction plans” for the developing embryo are encoded in the genetic material provided by the parents’ egg and sperm cells. Genes play the major role in determining most of the physical and chemical characteristics of your child—hair and eye color, whose nose she’ll have, and even whether she’s likely to have a high cholesterol level. Similarly, your child’s physical growth pattern is largely preprogrammed from the start, although his growth can be affected by nutritional factors, illness, and certain factors in the womb.

A special note: The information about physical growth in this chapter will deal with babies who were carried to term. Infants born prematurely will be smaller at birth.

“Don’t stress yourself out by tracking your baby’s development every month to make sure he hits every milestone exactly on time for the ‘average’ baby. No baby is average—some start to walk early, others a little later—and anything on a broad continuum is normal. So sit back, play, and enjoy him.”

Weight

In the United States, the average weight of a full-term infant is about seven pounds (90 percent of newborns weigh between five and a half and nine pounds). Lower birthweights are seen in premature infants and term infants who are small for their gestational age due to genetic conditions or medical problems during the pregnancy. Infants who are large for their gestational age are often those born to mothers with diabetes during pregnancy.

Don’t be surprised if your newborn starts to lose weight immediately after birth. During the first week of life, many infants will lose up to 10 percent of their birthweight as they get rid of some of the extra body fluid that the fetus accumulates while in the uterus. This weight loss tends to be greater in breast-fed infants and those infants who take in less fluid in their initial feedings. By age two weeks, your baby should be back at birthweight or above, and she should gain about one ounce per day through the rest of the first month. The rate of weight gain then slows, reaching a rate of about six ounces per month at age five years.

Weight gain in the first year is amazing—most infants will double their birthweigh by three or four months and triple their birthweight by twelve months! Toddlers, on the other hand, usually grow at about one-third that rate. That “fussy” two-year-old at the dinner table is probably just telling you that he doesn’t need to eat as much as he used to. It’s important to remember that, despite the smooth appearance of the curves on the standard growth charts, individual children do not grow at a steady pace.

Infants characteristically experience growth spurts during which they eat ravenously and gain weight rapidly for a week or two. Or a toddler may not gain any weight for a month or two through a rough winter stretch of colds and ear infections. When this happens, don’t worry. The large majority of infants and children will gain weight and grow in a pattern that is normal for them as they are well fed, are well loved, and have a stimulating environment. It is cause for concern if your baby is significantly underweight or fails to gain weight at the expected rate. This is called “failure to thrive”.

Although growth in height may also be slowed, the poor weight gain is usually more prominent. This condition is often the result of inadequate nutrition and/or environmental deprivation or neglect, but doctors will also evaluate a child experiencing failure to thrive for other underlying medical problems that can interfere with his ability to gain weight. In the United States and other developed countries where food is plentiful, excessive weight gain and obesity are much more common than failure to thrive.

Normally, infants have a higher percentage of body fat than older children do— most “chubby” babies don’t become obese children. However, approximately 30 percent of U.S. children are overweight, and that figure appears to be rising. Studies show that about one-third of adult obesity starts in childhood. It follows that prevention of obesity in childhood might prevent obesity in adults, which is linked to many health risks. Recent research indicates that genetic factors play a major role in determining whether a child will become overweight. It is likely, however, that a child’s eating habits and physical activity also have an important influence.

Parents should be aware that children under the age of two years shouldn’t be put on a restrictive diet, which can be dangerous at this age. If your child seems to be gaining too much weight, speak with your child’s doctor for advice.

Length and Height

In the United States, the average length of a term infant at birth is about 20 inches (90 percent of newborns will be between 18 and 211⁄2 inches long). Children grow approximately 10 inches in the first year of life, 5 inches in the second year, and then about 21⁄2 inches per year until they enter puberty. Don’t get too caught up in following your child’s growth on a standardized growth chart. A child’s growth in length/height is not completely smooth and constant. Some healthy children may not increase their height for weeks or months
and then go through a “catch-up” period of more rapid growth. Some research indicates that children’s growth rates may be seasonal—they seem to grow a bit faster in the spring.

A child’s rate and pattern of height growth are largely genetically determined and will follow that hard-wired course unless something interferes with it, such as chronic illness, malnutrition, environmental deprivation, or neglect. Although some parents may be tempted to try, giving a well-nourished child extra vitamins, minerals, or calories will not cause the child to grow any taller than his genetic potential.

Normal Variations

It’s not uncommon for healthy children (particularly during the first two years of life) to temporarily grow faster or slower than most other children their age and to change their position on the standard growth charts. For example, infants of mothers with diabetes and those born to mothers who gained large amounts of weight during the pregnancy tend to be larger at birth, but these babies usually grow more slowly over the first few months of life until they settle back down into a growth channel consistent with the sizes of their parents. On the other hand, infants of tall fathers who are carried in the small uterus of a petite mother may be smaller at birth than one would expect. These babies may grow quickly over
the first few months of life and “catch up” to their genetically predicted growth channel.

Children with short parents will usually start out small at birth, usually below the 5th percentile, and stay in about the same growth channel throughout childhood and adolescence. They will enter puberty at an average age, and generally they will reach an adult height similar to that of their parents. Another normal growth pattern found in some children is called constitutional growth delay. These children are usually of average size at birth, and their parents are usually average in height. After initially growing at a normal pace, these infants will grow more slowly, usually starting in the second half of the first year of life.

This slow growth continues until about 18 to 24 months of age. By then, the children often will have dropped below the 5th percentile line on the growth chart. From then on, they will grow about two and a half inches per year, which is similar to the growth rate of other children their age. Children with constitutional growth delay remain short through childhood. They begin their adolescent growth spurt at a later-than-average age (hence the term “late bloomer”). Because they continue growing after most of their peers have stopped, they “catch up” and reach an average final adult height similar to that of their parents. In many cases, a parent or other close relative of these children will have followed a similar growthpattern. Children who are extremely short or who have a persistently slow rate of growth may need evaluation for a possible growth disorder. This may involve referral to a pediatric endocrinologist or other specialist.

Head Growth

You’ve probably noticed that normal infants have relatively large heads. This is because most of the growth in the size of the brain takes place before birth, and brain growth is the major stimulus for growth of the head. At birth, the average baby’s head circumference (the distance around the head, measured just above eyebrow level) is 13½ inches (34 centimeters), which is about two-thirds of its adult size.

After birth, head growth continues at a rapid pace for the first year of life. From then on, the rate of growth slows, with the head and brain reaching near adult size around age 10 years. Your child’s doctor will monitor your child’s head (and brain) growth closely over the first two years by plotting head circumference measurements on a standard growth chart at each checkup. Small head size or slower-than-expected head growth can occur in infants with a variety of problems, including birth defects of the brain, intrauterine infections or exposure to toxins, abnormal growth of the skull bones, and a number of nutritional, genetic, and metabolic conditions. An overly rapid increase in the size of an infant’s head can be a sign of excessive buildup of fluid and pressure within the head, as seen in the condition hydrocephalus.

What parents don’t get excited and glow with pride when their little one takes her first steps at an earlier age than anyone else in the family? And what parents don’t get a bit concerned if their son continues to merely point and grunt when he wants something, while all the other kids in the playgroup seem to be adding new words to their vocabularies every day? Comparing a child’s developmental progress to that of other children is a popular pastime of parents and grandparents. Although it’s human nature to make these comparisons, there is great variation in the way normal infants and children grow physically, and their rates and patterns of development differ widely as well. You should rely on your child’s doctor to assess and track development at his regular checkups. A child who isn’t keeping pace with his peers developmentally may have a problem that needs attention.