For a newborn baby, the outside world is a frightening but exciting place. The first year is a foundation year, during which a normal baby acquires basic skills that will be built upon through the rest of its life. For instance, in these months the baby’s eyes, ears, and tongue develop abilities that will be necessary for learning to read and speak. The baby begins to learn how to control its muscles; it also experiences emotion, and begins to understand language. It grows its first teeth and learns to smile, laugh, and eat solid food.
An average newborn baby weighs 6-9 pounds (3-4 kilograms) and is approximately 20 inches (50 centimeters) long. By 12 months, it weighs roughly 19-26 pounds (9-12 kilograms) and has increased its height by approximately 28-33 inches (70-80 centimeters). A newborn baby’s brain is around 25 per cent of its final adult brain weight, although the baby’s body is only 5 per cent of its adult weight. During the first year, the brain grows very fast, allowing the baby to learn an enormous amount.
A newborn baby’s skeleton is soft and incompletely formed, and its skull has gaps (fontanels) between the main bony plates. This softness and flexibility allows the baby to pass through the mother’s birth canal without damage. The fontanels close during the first 18 months, and the bones harden as the child grows. In fact, the whole process of ossification, which changes soft cartilage into hard bone, begins before birth and continues until about age 20.
In the first 12 months, the skeleton strengthens until the legs are able to support the baby’s weight. The first tooth usually appears about the sixth or seventh month, at about the same time the baby begins to take bottled milk and solid food.
Reflexes and senses
Newborn babies show a number of instinctive actions and responses known as reflexes. They include the rooting reflex, where the baby turns the head if the cheek is gently touched; the grasp reflex, in which the hands tightly clutch anything placed against the palm; and the stepping reflex, in which the baby steps when a foot is placed on a horizontal surface. These reflexes are later superseded by more complicated reactions, such as turning toward a familiar sound, and reaching out to grasp an object the baby can see. By 12 months, a baby has developed the full width of vision he or she will have as an adult, and can focus on small objects at a distance.
From the earliest months, babies gaze longer at patterned and colored shapes than at plain white or gray ones. A normal baby’s hearing develops rapidly, and improved coordination helps it to turn toward sounds it has located. By eight weeks, a baby utters the first recognized phonemes sounds that later join to form speech. By one year old, he or she has mastered some of the more difficult sounds, such as “b,” “g,” “p,” and “t”; many babies say their first recognizable words just before the first birthday.
A baby’s motor (movement) development is very rapid; through the first 12 months, it develops from a helpless infant into a mobile, inquisitive individual. Noticeable muscle control begins at about three months, when the baby can hold up the head. As the limbs and muscles strengthen, coordination improves and, by about six months, a baby is able to roll over and sit up without support; by about nine months, he or she can reach a standing position; and by about 12 months, the baby walks when one hand is held. The baby learns first to clutch objects in a closed fist, then to grasp them with the thumb on one side and fingers on the other, and then to pick up fairly small objects with finger and thumb.
Personality and emotions
In the mother’s womb, a baby is comfortable, warm, dark, and soothed by the mother’s heartbeat, so for the first few weeks after birth, bright lights, loud noises, and sudden movements can be very distressing. Babies gain tremendous pleasure and security from warmth and physical closeness, and benefit from as much as they can get.
By about six weeks, the baby has learned to smile, and at four months he or she laughs and giggles. By its first birthday, a baby is able to respond to simple commands, such as “come here,” and to understand the meaning of “yes” and “no”; babies love imitating adult behavior, and will “burble” contentedly, although incomprehensibly, while playing. In these vitally important, formative 12 months, the foundations are laid for all types of adult behavior, emotions, and skills.
Babies receive some immunity from the mother before birth, and some from antibodies in breast milk. Nevertheless, they are vulnerable to infection and so are usually immunized against certain infectious diseases between birth and 18 months, with a booster dose at about age 5. Inoculations against diphtheria, pertussis, tetanus, and poliomyelitis are the most common. Vaccination against hepatitis B, hemophilus, measles, and mumps is also available.