Arlene,
Your astute question reinforces the critical importance of getting it right when a writer creates fictional children. If your story spans months (for infants) or years (for older children), then the writer must deal with changes in physical and mental attributes. It’s very hard to be a virtual parent! Pediatric attributes are constantly changing. Attributes such as height, weight, mental capacity, eye-hand coordination, developmental milestones, nutrition, health issues, disabilities, injuries, educational achievements, congenital defects, and more, must be accurate in order to keep your fiction real.

Here are three quick resources that will help to get you started:

1. For info on general height and weight through the early ages go to:

http://www.cdc.gov/growthcharts/...

This is divided into two sections. The WHO charts are for children ages 0-2 years, and the CDC charts are for children 2 years and up.

2. For a quick check of normal pediatric growth and developmental behavioral milestones go to:

http://www.cdc.gov/NCBDDD/actearly/milestones/index.html...

This is divided by ages, so you can reference each section as a check on the behavior of each of your child characters, and keep their behavior appropriate.

3. For more detailed info on every stage of child development, the following website is nicely indexed by age groups and specific areas of child development. It contains a good mix of basic info on healthy children of all ages, and articles on childhood health issues.

http://www.healthychildren.org/English/Pages/default.aspx...

H.S. Clark, MD