Healthy infants come in a range of sizes, and there is a wide range of “normal development”. That said, infant growth tends to follow a predictable path. During infancy, children experience the largest percentage of growth in their entire life. Here are some general guidelines for growth in the first year of infancy:

• From birth to age 6 months, a baby typically grows 1/2 to 1 inch (about 1.5 to 2.5 centimeters) a month and gains 5 to 7 ounces (about 140 to 200 grams) a week. Most babies double their birth weight by 5 months old.
• From ages 6 to 12 months, a baby typically grows 3/8 inch (about 1 centimeter) a month and gains 3 to 5 ounces (about 85 to 140 grams) a week. Most babies triple their birth weight by their first birthday.

Imagine what that growth pattern would look like as an adult! An average sized woman (150 pounds) would be 450 pounds in twelve months! It is important to realize that as infants grow physically at an exponential rate, they also make great strides in their cognitive, social and emotional development.

Keep in mind that many healthy babies go through brief periods when they stop gaining weight or even lose a little weight. A doctor is only likely to be concerned if a baby doesn’t gain weight from one well-baby exam to the next. A baby’s position on the curve in a growth chart isn’t as important as the trend of the curve overall.

The average North American newborn is 20 inches tall and weighs 7½ pounds. The average 2-year-old weighs 26 to 32 pounds and is 32 to 35 inches tall, almost half of their adult height. Growth slows considerably in the second year.

Children experience two growth patterns during infancy. The cephalocaudal pattern of growth is growth from the head down. Children often appear “top heavy” with their heads proportionally larger than their bodies. The proximodistal pattern of growth starts at the center of the body and moves toward extremities. Infants have control of the trunk of their body, then their arms, then their hands and fingers  (Santrock, 2013).

The brain develops extensively in utero and during infancy. Neurons, or nerve cells, are present in the brain at birth. Shaken baby syndrome is a cause for concern. Shaking a baby causes brain swelling and hemorrhaging. Neurons help process information. The myelin sheath is a layer of fat that insulates nerve cells and makes information processing happen more quickly. Experience is like little bursts of electricity to the brain, igniting the neurons. Brain development occurs when certain areas bloom through experience. Experience helps to develop the brain., and an infant’s brain is waiting for experiences to determine connections among neurons.

Sleep is extremely important during infancy because it helps to promote brain development. At about four months, the infant has more adult-like sleep patterns. The length of sleep patterns is related to sleeping arrangements and parental activities. Sharing a bed is common in many cultures; however, in the U.S. most infants sleep in a separate crib in a separate room. Co-sleeping is discouraged because of the risk of SIDS.

SIDS, or Sudden Infant Death Syndrome, is a condition in which an infant stops breathing, usually during the night, and dies without apparent cause. There are increased risks if a child is of lower birthweight, has sleep apnea, sleeps on their stomach, is exposed to cigarette smoke, has a sibling who died of SIDS, is sleeping in a very warm room, or is using soft bedding or bumpers.

Another crucial factor for healthy development in infants is nutrition. Healthy infants need 50 calories per day per pound of weight. Fat is especially important for growth and brain development. Infants should not be put on a low-calorie diet. Breast milk is the ideal food for an infant although there are many healthy formula options as well. Breast feeding is recommended because it reduces allergies and infections, lowers obesity risk, is free, promotes cognitive growth, lowers the risk of SIDS, and fosters better visual acuity and bone density. It is often the only safe option in poor countries where unclean water makes mixing formula impossible. There are two serious conditions infants can develop if they are not receiving proper nutrition. They can develop marasmus, a wasting away of body tissues in an infant’s first year caused by a severe lack of protein, or kwashiorkor, a deficiency in protein that causes the child’s abdomen and feet to become swollen with water. The effects are extremely detrimental and can even cause death.

One way to help ensure an infant’s health is to have them immunized. Immunization begins in infancy and prevents many diseases including measles, mumps, rubella, hepatitis, and chicken pox.

Infants’ first actions are reflexes. The rooting reflex is the reaction when an infant’s cheek is stroked. The infant turns towards a food source. The sucking reflex is automatic sucking when something is placed in the newborn’s mouth. The moro reflex is a startle response that causes rapid closing of arms and legs. The grasping reflex occurs when something touches an infant’s palm and they automatically hold onto it.

Infants develop fine motor skills and gross motor skills in infancy. Fine motor skills are small muscle activities, such as coordinating the thumb and forefinger and reaching for and grasping objects. Gross motor skills are large muscle activities, such as pulling toys, climbing stairs, walking and running.

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Infant Gross Motor Skills

Infant Fine Motor Skills

Infants reach motor milestones in diverse cultures based on opportunities. However, the variations are not large. Milestones are reached within normal age ranges. During the sensorimotor stage (birth to 2 years), Piaget believed that infants learned through their five senses and fine and gross motor skills. Piaget argued that children need to have multi-sensory, hands-on experiences to better understand their world. Sensation is the actual feeling someone has. It occurs when information contacts sensory receptors-eyes, ears, tongue, nostrils and skin. Perception is the interpretation of sensation, what someone thinks about what they feel. The more sensory experiences an infant has, the stronger their perceptual development. Since infants cannot talk, it is sometimes difficult to understand how they are perceiving the world. It is known that when infants use all five senses: sight, hearing, taste, touch and smell, they create perceptions about their experience. The more infants interact with their world, the more they learn and grow. Caregivers can help foster a strong learning environment by observing how infants are responding to a particular situation. Habituation occurs when an infant becomes bored with a stimulus. Dishabituation occurs when an infant becomes reinterested after a change in stimulation. It is the job of a caregiver to recognize when an infant requires more stimulation or needs a break from a specific activity.

How young do infants begin to use their five senses? Young infants have depth perception. They perceive clear patterns as well as color. Their eyes are drawn to red as well as a clear black/white pattern. Hearing begins in the womb. Touch and pain are experienced at birth. Smell is present shortly after birth, while taste may exist even before birth. Since all five senses are engaged in early infancy or even before, the importance of sensory experiences cannot be underestimated. Creating an environment that incorporates all five senses and fine and gross motor experiences is crucial to infant development (Gordon & Browne, 2017).