Lesson06
Chapter 5 - Physical Development in Infants and Toddlers
For those of you who have children of your own (and for the rest of you who've spent significant amounts of time with young children), you've probably noticed that the physical growth of young children happens rather quickly! If you can picture a newborn baby who averages 20 inches long and take into account that by the time this child reaches 2 years old they'll be half of their full adult height, that's a lot of growing that takes place in a fairly short amount of time! I want to do a quick review of some basic growth statistics, and then we'll move on to the growth that isn't quite so obvious - the growth that we influence every time we interact with these little ones, and that ultimately will effect their abilities and opportunities for the rest of their lives! The average full term newborn is about 20 inches in length and weighs around 7 pounds. Most newborns also lose about 5-10% of their body weight during the first few days of life, which tends to catch most first time parents a bit off guard! This is perfectly normal and healthy, since many newborns are quite tired from their journey into the world, and while they are getting nutrients from nursing, they aren't taking in quite as many calories during these first few days of life. By the age of 1, toddlers have tripled their body weight, and are now averaging around 22 pounds. They've also added a few inches in height, and now average around 30 inches tall. By the age of 2, toddlers average around 30 pounds and around 34 inches in height. Remember, most 2 year olds have reached half of their full adult height at this point, so you can generally get a pretty good idea of how tall or short someone may be later in life. It's also important to remember that these are averages - as long as a child is growing, most pediatricians aren't concerned if they are under or over the average. However, a child who is significantly under or over the average is probably a child that should be checked by a pediatrician since this can be a sign of "something not quite being right". Every child is different and grows at slightly different rates, and every child got their DNA from their parents - so look to parents for indications of why a child might appear above or below the average (in other words, two tall parents are likely to create a tall child). What can effect growth beyond genetics are nutrition and overall health.
One thing we have seen quite a bit of change in over the years is the survival rate of infants. We are now seeing many premature babies, born as early as 22 weeks gestation (remember, 40 is full term), surviving and living long and healthy lives. We have seen such amazing technological advances during the past century, which also include improved immunizations and sanitation, which are also contributing to the improved survival rate of these little ones. In addition, we also have more parents receiving parent education, which includes prenatal care early in a pregnancy. However, the second most common cause of infant death today is SIDS (Sudden Infant Death Syndrome), which to date has no known cause - what we do know is that males who are 2-4 months old, born in the winter, and who sleep on their stomachs are at the greatest risk. Motor Skills Newborns first motor skills are limited to reflexes. Breathing Reflex - maintain adequate oxygen Maintaining body temperature by crying, shivering and tucking legs close to body. Foster feeding through sucking reflex, rooting reflex, swallowing and crying. Babinski reflex - toes fan out when the foot is touched from heal to toe Rooting reflex - when baby's cheeck is stroked, it turns its head toward the stroking and opens its mouth Palmer grasping reflex - baby grasps an object placed in the palm of its hand Moro reflex - baby throws its arms out and then inward in response to loud noise or when its head falls Within the first four weeks of life, a baby will gradually develop skills from the reflexes to sustain life, and the basic reflexes will begin to disappear. The following is a basic guideline of development over the first year - and remember, while the order that development occurs in within each area is generally the same for each child, the timing listed is an average age - each child will develop these skills when ready! Gross Motor (larger physical movements, such as walking or running) o 8 months - crawl o 9 months - walk with assistance o 10 months - stand alone momentarily o 12 months - walk well unassisted o Once walking, considered a toddler
Fine (smaller physical movements, such as picking up things with fingers or hands) o infants use whole hand to grab o 6 months - reach, grab and hold on to objects o 9-14 months - use thumb and finger to grasp Sensory and Perceptual Capacities o newborns can see 4-30 inches away at birth (20/400) o by 12 months, vision reaches 20/20, or as good as it will get o binocular vision occurs around 3 months (ability to track and follow objects) o full color vision occurs at 3-4 months Hearing o accurate at birth (or as good as it will get) It's really important for new parents to recognize when these skills develop. To give you an example of why, I'm going to share with you an experience I had with my father when his first granddaughter was born. My niece would reach out to her parents or any other adult and grasp on to their hair. She wouldn't do this with my father, who then shared with me that he thought his granddaughter didn't like him. I then explained to him that every other adult in the room had quite a bit of contrast between their hair color and skin color, and this little 2 week old baby couldn't see color - just contract (remember, they don't see color until 3-4 months). My father has gray hair and pale skin, which meant no contrast - nothing this little baby could identify! I put my niece on the floor and had my father walk to different parts of the room and talk to her - and she would turn in his direction every time! He was then convinced his granddaughter loved him after all! While I'm sure she did, I made sure to demonstrate skills I knew she had.....which also helps parents to bond with their newborns. While many parents feel a bond with their unborn child, many other parents don't - they require their newborn to respond to them to "feel" that bond, such as by demonstrating that newborns recognize voices they've heard prenatally (such as mom & any other person heard frequently, like dad or siblings) or the Palmer reflex to "hold" the hand of a parent or sibling.
Brain Growth Newborns are born with most of the neurons they will ever have within their nervous system. Maturation consists of the growth and branching of the neuron's dendrites into networks. As the nervous systems mature, neurons become coated with myelin,
which increases control over motor functions and sensory abilities. This process proceeds the fastest from birth to 4 years old (the brain will reach 90% of its adult weight by 5 years of age), but continues through adolescence. OK, so what does this mean? Picture a 9 month old taking his/her first steps. These steps contain many of the skills this little one has been "mastering" since birth, so the "newness" of the step is really the combination of existing skills to create a new skill. All of the existing "skills" exist within the neurons. The ability to combine to skills to create a movement requires the connection of two neurons, and it's the development of dendrites which connects the two neurons. If you've ever seen a first step, they tend to be very stiff and unsure - this is because there is no myelin coating on the dendrite. As the myelin coating develops, the movements and skills look more like those of adults. And what it is that causes the growth of dendrite networks and their myelin coating to develop? This is still an area that is being researched, but there are a few things we know for sure - children who are stimulated at just the right amount (a child who is interacted with by people, environment, etc) develops more connections than a child who is understimulated (ignored or left alone) or overstimulated (too much happening in the environment causes the child to look away or "turn off" too much stimulation). We also know that the fat content in breast milk or formula, as well as whole milk up to their second birthday, is necessary during the first two years of life to aid in the development of dendrite connections and their myelin coating. We'll talk more about the dietary issues in a moment..... what is important to realize is that brain growth and development primarily occurs during these first few years of life. When we talk about child maltreatment (abuse or neglect), or even the pros and cons of child care versus family care at home, brain development and stimulation is something that should be considered. Nutrition When we discussed above the necessity for breast milk or formula for healthy brain development, you might have already been aware of the fact that there is still a huge controversy over the "ideal" food for infants and toddlers. Lets talk about this for a moment. We know that breast milk is the most ideal for babies. Breast
milk provides them with all essential vitamins and iron for healthy growth. Breast milk is more easily digested. Breast milk also provides immunity to diseases. Breast milk being the "ideal" option also assumes that mom has enough breast milk to sufficiently feed her newborn(s). Many moms want to continue providing breast milk, but if the body stops producing, little can be done to begin producing again. Breast milk being the "ideal" option also assumes that mom has the flexibility and desire to "pump" breast milk when not with her newborn, such as after returning to work (which happens for many new moms between 4-6 weeks after delivery). Breast milk being the most ideal is assuming that mom is healthy. For many new moms, medications that can't be taken during a pregnancy will be required after giving birth (and many other moms require antibiotics following a delivery, which prevents breastfeeding). In reality: Less than 1/5 of the US babies are breast fed for more than six months, and most are for less than two months (many employed moms try pumping for the first few weeks back at work, and the inconvenience or discomfort often prevents continuing beyond a few weeks) Cultural attitudes, protection of infant, and convenience are the primary reasons why people choose not to breastfeed, or choose not to breastfeed beyond 2-6 months Formula, when mixed appropriate with the right percentage of powder and water, provides all of the essential vitamins and iron for healthy growth! In areas where tap water isn't safe to drink, bottled water is necessary for the health and safety of the child. By around 6 months, solids such as cereal or rice fortified with iron should be introduced to a child's diet. A baby is born with enough iron within his/her system that supplements aren't necessary until around 6 months, which is why most doctors will recommend starting an infant on cereal or rice around 4-6 months of age. Introducing solids sooner than this can hurt an infant, since their digestive system isn't developed enough to process solids much earlier - although some doctors will recommend very small quantities a bit earlier in development.