Most books on child development include charts of some sort outlining the normal milestones that children reach as they grow older. Parents can look up the ages of their children and see what those children “should” be doing. A 9-month-old, according to a typical chart, will show a fear of strangers and can hold her own bottle. Such charts often include a note explaining that parents should expect and accept as normal a certain amount of variation in the ages at which children can perform the tasks described.

Unfortunately, those warnings are often ignored. The fact that the information is in a chart and that it involves numbers makes parents take these charts too literally and give them too much importance. Holding a bottle and becoming fearful around new people are behavior that do not magically develop on the first day of the ninth month of life. (In fact, there’s evidence from several studies that the fear of strangers that parents were told to expect from their 9-month-olds does not appear at all in a significant number of infants.) This leads parents to become unreasonably upset if their child is “late” or inappropriately happy if their child is “early.”

Success Isn’t Dependent Upon Age

When it comes to developmental markers of any sort, the most important thing to remember is this: The fact that a child reaches a marker or passes through a stage is almost always more important than the age of the child when he or she does it. In other words, unless your child is extremely late, it doesn’t matter when she learns to hold a cup by herself, learns to walk, becomes toilet trained or does any of the thousands of other little and big tasks that we pay so much attention to as a measure of her progress — as long as she achieves them.

A classic example of this is toilet training. In the long run, it really doesn’t matter if a child is successful at age 2, 3, 4, or even 5 years old. (Beyond that age, we start to get more concerned.) Yet many parents become upset if their child appears to be lagging behind his age-mates. One question I ask these parents is whether, before they were married, they asked their prospective spouses the age at which they had been toilet trained. I have yet to find anyone who actually asked! My point is that while it feels so important at the moment, in the long run the timing really doesn’t matter as long as the child is successful.

If a child reaches the developmental markers in these typical charts a month early or a month late, it’s usually no big deal. As a child grows older, reaching a milestone even a year early or a year late doesn’t really matter. The patterns of development are much more important than the precise timing.

This is not to say that such charts or guidelines are useless. Quite the contrary, they help orient us to the patterns of child development and warn us of possible problems. If, for example, an infant cannot hold a bottle by the time he’s a year old (i.e., well past the average age at which most children do this), you probably should see a pediatrician about the problem. If a child still can’t read by the end of second grade, you should insist on his undergoing some testing for learning disabilities and getting special help for him before the problem becomes more difficult to solve.

Physical Development Stages

The developmental patterns presented in typical charts of physical development can also be seen through the universe of children’s behaviors. The stages of physical development are fairly clear-cut and readily observed. Newborn infants will show what appear to be random but symmetrical movements of their arms and legs. During the next stage of development, which usually occurs somewhere around six months of age, they will begin to reach for specific objects with their arms. A few months after that they will have enough control of their hands to use them as pincers for picking up small objects. Somewhere around one year of age most children can reach for small blocks or rattles, pick them up, and, if they’re in the mood, give them to you if you hold your hand out.

Language shows similar discrete, if fuzzy-edged, stages of development. Within three months or so, most infants will progress from only crying to a form of cooing or making certain simple vowel sounds. The ability to form consonants, especially the sound mmm, comes a few months after that. (Children who say “mama” before they say “dada” may be telling us more about their neurological development and coordination than about their preference for a parent.) After a few more months they usually respond to their name and certain frequently heard key words such as “NO!”

Somewhere around one year of age the child will start using words, especially nouns. After another year or so the child will know a couple of hundred words and will be able to tell you the names of some objects in picture books — a very important step since a picture of a dog or a chair is very different from a real dog or chair. By the time children are ready for preschool they know about a thousand words and will soon begin saying complex sentences such as, “You can watch me draw a picture.”