Monday, May 14, 2012

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.

By four months she will double her birth weight, and by her first birthday she'll triple that. Her second year will be a bit slower - by age 2 she'll weigh about 30 pounds and be around 3 feet tall. The average 2-year-old is just about half her adult height and many doctors will predict adult height based on their 2-year-old check up. Your doctor will use height and weight of your baby combined to determine if her growth is healthy.

Babies spend most of their growth time asleep - about 17 hours a day when they're still new. If you try to conform your new baby's sleep schedule to yours it can be harmful to her and a pain for you, so allow for her to sleep when she needs it. Valuable research on co-sleeping is available, a way for the baby to sleep with you and be fed the moment she stirs. You will sleep more this way and baby will get just as much sleep as she needs too, but co-sleeping isn't for everyone. You should determine if your baby belongs in your bed, in your room, or in another room.

You may notice that one of baby's biggest growths is in her brain. By age 2, her brain will be almost 75% of it's adult size, so your doctor will also keep track of head circumference at check ups. Baby will be born will all the neurons she needs, and a few extra, so as her brain develops, pruning will occur. Pruning, much like cutting away unnecessary parts of your rose bush, is your baby's brain cutting away unused neurons and dendrites  to allow the others to grow. Dendrites grow and connect your baby's brain cells so she can function and grow on the outside too.

As your baby's brain matures, her outward experiences will shape it. Some functions of her brain require basic experiences to develop, and other functions depend on certain experiences - they may or may not develop. The experience-expectant functions absolutely have to happen for normal brain development, such as interaction with other people. The latter, experience-dependent brain functions are more like the words we learn; each set of vocabulary is unique to the experiences we have had. Your baby depends on you to enrich her brain, but she will develop fine so long as she has basic interactions.

Fortunately for all of us, baby is born with a drive to remedy her deficits and guard against malnutrition. Her brain will keep growing even if she isn't getting enough food thanks to head-sparing. She should also develop normally even if she doesn't have the latest in educational toys thanks to self-righting. These two natural biological drives keep baby on the path to seeming indestructibility.

If a toddler has 75% of her adult brain weight, why not 75% of her adult functionality? The last part of her brain to develop is her prefrontal cortex. This is where planning and control are handled in the brain. Your toddler has a tantrum because she doesn't know how to stop one yet. But be careful! Just because your baby cries doesn't mean she has an off-switch. This can frustrate parents and lead to shaken-baby syndrome. If you shake your baby too hard, her brain will bounce around in her skull, rupture her blood vessels and break her neural connections. Your baby will stop crying - either because she has been brain damaged, entered into a coma, or died.

Even though baby will naturally protect herself against many ills - she cannot guard against all of them. She'll work hard to self-right in stressful situations, but you'll have to help her along so she doesn't spend all her time like this:

So baby's experiencing her first sensations and begins to see, touch, hear, smell and taste. As soon as she comes into contact with something she has sensed it, and her not-so-little brain jumps into action to process and perceive what it is. By about 4 months of age she can perceive her own name; by 6 months she will respond to it. Hearing is her most acute sense at birth, as she has already been listening to you through your third trimester of pregnancy. Your doctor will most likely check her hearing at birth. Sight is less developed: at birth she can only see things between 4 and 30 inches away, but by 2 months she can recognize and respond to faces. At 3 months she will look even closer, at your eyes and mouth and before 4 months her eyes will start working together, an ability called binocular vision.

The other senses adapt quickly to the world around your baby. The five work together in harmony for two purposes: social interaction with caregivers and comfort from the disturbances of infant life.

Baby's motor skills kick in soon, starting with the simplest reflexes such as sucking, breathing and shivering. These reflexes keep baby alive - sucking to drink milk, breathing in air and shivering to warm themselves when it's cold.

Skills such as walking and jumping are called gross motor skills - large movements that incorporate the whole body. Harder skills to master such as finger movements to write are known as fine motor skills. Those will come later on.

You and baby are lucky to be around now. These days, 99.9% of babies who survive their first month in the healthiest nations will live to at least age 15, and even in the lower-ranking nations, about 75% make it too. There are plenty of immunizations available for diseases that used to take so many small children. Some of the most dramatic successes with immunizations include:

  • Smallpox - eradicated worldwide in 1971
  • Polio - eradicated from most nations (the US included)
  • Measles - down to only 37 cases in the US in 2007

These are some of the diseases they teach you about in elementary school that plagued the world and brought us to our knees. Thanks to these and other immunizations, we continue to improve health-wise. Unfortunately, "no one notices when things go right." Disease prevention has done so much for us, but the efforts are widely under-appreciated.

One of the things you may be most worried about in baby's first months is SIDS - sudden infant death syndrome. Babies who die of SIDS seem perfectly fine and healthy and suddenly are gone. In 1990 about 1 in 800 infants died of SIDS. Many doctors advise that baby should sleep on her back to lessen the chances of SIDS, but this does not prevent all SIDS deaths. Most babies who die of SIDS are between 2 and 6 months old.

As for baby's nutrition - breast is best! If you are unable to breast-feed, you shouldn't feel bad, but the benefits of breast-feeding are much higher than those of formula. Breast-fed babies have fewer allergies, get sick less often, fewer cavities, and even higher IQs. Mother can bond more easily with baby and her breast milk changes to suit baby's needs, even giving her the antibodies she needs to stave off incoming infection.

As you can see, baby will probably turn out just fine and you can help her along on her way to being a happy, healthy toddler.

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