Amazing Facts About Infant Development

Babies have all their brain cells, or neurons (some 100 billion), by just six months in the womb. However, these cells remain poorly connected until months after birth.

At birth, babies' brains have very little white matter or myelin, the fatty substance that dramatically speeds up information processing. As myelin is gradually added to their brains, babies' perception increases and they move more quickly and efficiently.

Newborn babies are more alert for the first two hours after birth than they will be for the next week or two. This is due to stress hormones released during delivery, which arouse babies, dilate their pupils and promote bonding with their new parents.

Young infants recognize their parents and other familiar caregivers by smell. In fact, their sense of smell is much sharper than the senses of vision and hearing in the first few months of life.

Babies begin learning the difference between languages even before they're born. They don't understand the words, but can recognize the distinct musical tones of different languages.

Babies can recognize familiar songs or stories that they were repeatedly exposed to before birth.

Touch sensitivity develops in a head-to-toe sequence in babies. For example, young infants detect different textures more acutely with their lips than with their fingertips.

Babies sense motion and gravity using the inner ear, or vestibular system. This is one of the earliest senses to develop and is responsible for many newborn reflexes, such as the Moro response. Also known as the startle response, this reflex action is characterized by the flailing open of a baby's arms if he or she has a sudden sensation of falling.

Pediatricians test the vestibular system by turning a baby's head from side to side and looking for eye movements in the opposite direction: when the head turns right, a baby's eyes will move left, so that they stay focused on what's in front of them. This is called the doll's eye reflex because it is similar to the movement of the weighted eyes in old-fashioned dolls.

3-D vision emerges quite suddenly in infants between about three and four months of age, and earlier in girls than in boys.

Baby's sense of hearing begins before birth. By birth, a newborn has been listening to mother's voice for at least three months and can distinguish it from other women's voices.

Newborn babies can see, but not very clearly. Their vision is 20/600 and they cannot see well directly in front of their faces.  A newborn can actually see better out of the corner of his or her eye.

Their sense of taste is well developed at birth, however, the ability to detect saltiness does not emerge until about four months.

Read more from Lise Elliot, PhD, Author, What's Going On in There?