Early Childhood: Biosocial Milestones

After baby makes it through her first two years and officially becomes a toddler, everything is different. Between the ages of 2 and 6, baby grows from a chubby, toddling thing into a much more mature being whose body and brain is practically adult compared to just a few years before.

Baby's BMI at age 5 is lower than any other time in her life. Her chubby belly, round face and short limbs are replaced by a slim frame at she lengthens out and grows muscle. She suddenly looks much more like a gymnast than the infant she was. Every year between the ages of 2 and 6, your healthy baby should gain nearly 5 pounds and grow about 3 inches. By age 6 she is approximately 46 inches tall, weighs 46 pounds, and her legs are about half of her height - meaning she has adult-like body proportions.

The First Two Years: Psychosocial Milestones

The last facet of baby's first two years is her psychosocial development. Put simply, it is her emotional reactions to the world.

Baby's emotions start off rather simple. At birth there is crying and contentment. By six weeks she smiles to be social and by 3 months it becomes laughter and curiosity. By 4 months she has a big responsive smile and starts to experience her first anger (more evident by 6 months). Between 9 and 14 months she'll grow a fear of social events, strangers and separation as well as unexpected sights and sounds. By 18 months she'l be rounding out her emotional spectrum with self-awareness, pride, shame and embarrassment.

The First Two Years: Cognitive Milestones

So we know about baby's growth on the outside, but let's talk more about what goes on in her head during the first two years.

When it comes to cognitive development, the first place to go is to Jean Piaget. He was the first to demonstrate through research that infants really are intelligent and gave us insight into what baby's brain. His stages of cognitive development are the basis for what we know about baby.

The First Two Years: Biosocial Milestones

You just had a baby! And oh, baby what a baby it is! In the first months and years of life, that baby is going to accomplish more than you can even begin to comprehend.

The most obvious accomplishment in the first two years of your baby's life will be growth. Anyone can see that babies grow so much, even in a matter of days. If your baby was the average baby, she weighed about 7.5 pounds and was about 20 inches long when she was born. These are norms, meaning the standard for a population. She may seem tiny now, but this will change over the next days and months.