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Physical Changes in Infancy: An Exclusive Guide

Physical Changes in Infancy: An Exclusive Guide

Physical changes in infancy are one of the most important tasks which the infant performs. From birth till the end of infancy, an infant doubles his/her height and triple the weight. An infant’s development happens in two directions: horizontal and vertical. From head-to-toe development is considered vertical. Whereas from chest to hands is defined as horizontal.

Every baby is different from others and acquires physical development in his/her own developmental pattern. Some infants are speedy in physical growth, but others are slow. It is observed that girls are more active and speedier to acquire developmental milestones rather than boys.

But still, there are four main domains that every infant cover during infancy. These four domains are physical development in infancy, language development, social development, and cognitive development.

Physical Development From Birth to 24 months

Physical changes in infancy are the most prominent growth which we can observe in an infant. It starts in the head in the first 2 months an infant becomes able to lift and turn his head while laying. Then the physical development in infancy moves to the other parts of the body, like sitting, standing, and walking. According to developmental psychology, proper nutrition or adequate nutrition affect infants’ physical growth.


If we talk about infant development in terms of height or length. An infant grows around 10-12 inches in the first year. The head initially makes up 25 percent of the healthy babies’ height. By the end of infancy around 24 months, old infants achieve half of an adult’s height. 


A healthy physical development can be observed in terms of good weight. According to the health and human services a healthy infant who gets a proper diet, especially breast milk would triple his birth weight by the end of 1st year. At the end of infancy, a 2-year baby is expected to gain 26.5 pounds which are 12 kg. Infancy is also known as an era of rapid growth and dramatic physical change.


Teeth are other prominent physical changes that an infant shows in infancy. Typically, infants start growing teeth at the age of 6 months. By the end of 2-3 years, an infant completes the set of 20 teeth. This is called the teething process; this time is really difficult for both baby and the primary caregiver.

Because an infant feels so much pain in the head, itching in the ears, and feels so irritated which makes him cry a lot. Most babies use the sucking reflex and put everything in their mouth. These things contain germs and cause vomiting and diarrhea. Infants typically lose weight due to all these difficulties.

The teething process usually gets at its peak at night times, so a mother should prepare herself for sleepless nights. Still, a proper amount of water and calcium can give relief to babies in this tough time. You can also get help from this article to make a baby sleep very well.

Most dramatic physical change

Human brain development is the most dramatic physical change that takes place in the first two years. Brain gains 75 percent of its adult weight. Heart, lungs, kidneys, liver, etc. continue getting maturity with the passage of time. These parts are also included in physical changes in infancy.

We cannot observe their development of them but they keep on developing inside. Although normal height, weight, and activeness show that these parts are working properly.

Motor Development From Rolling to Walking

In terms of motor development, we can clearly observe physical changes in infancy. Here we can also have a clear sight of vertical and horizontal development. We can also observe voluntary movements and involuntary movements.

First, infants learn to control their head, neck, and then down parts of the body. This happens due to the physical development of the neck muscles. This is vertical growth. Talking about horizontal growth, an infant gets control over his chest, then starts operating with his arms. And lastly, an infant learns to manipulate his fingers. There are two types of motor skills fine motor skills and gross motor skills.

Gross Motor Skills

Describing early milestones, when an infant uses large muscle groups and performs some tasks that are known as gross motor skills. Gross motor skills are rolling, sitting, running, jumping, climbing, blinking, grasping, sucking, rooting, walking, and stepping. These are also known as typically large movements of infants and toddlers. By the end of infancy, an infant can shift from a standing position to a sitting position.

Development of neck muscles and holding the neck properly is also a gross motor skill. If an infant does not perform these basic gross motor skills then parents need to be alert. This is known as developmental delays which some infants and toddlers experience in their lives. They should get a proper checkup on that child and examine child development.    

Fine Motor Skills

On the other hand, when an infant uses smaller muscles to perform any task. That is known as fine motor skills. In motor development, fine motor skills are considered more mature than gross motor skills. Some fine motor skills are holding things, writing, drawing, painting, buttoning clothing, turning things, eating, and cutting with scissors.

The grasping object involves small hand muscles this is why grasping is also a fine motor skill. Normally by the end of infancy, an infant easily performs all these fine motor skills. They can grasp objects voluntarily. But large muscle groups stay in coordination to perform these fine motor skills.

Cognitive development

Cognitive development is more complex than the apparent physical growth in infancy. It refers to an infant’s learning ability, memory, thinking, and reasoning. The development of the central nervous system improves the cognitions of infants and toddlers. Experimental child psychology proved that infants are born with the capacity to recognize their primary caregivers.

This is why mostly an infant feels comfortable in the lap of the mother but cries in other hands. This is the first sign which depicts cognitive development. Typically an infant performs the following tasks at the end of infancy even if he is an average newborn.

An infant is playing with blocks and showing physical changes in infancy.
An infant is playing with blocks and showing physical changes in infancy.
  • An infant’s ability is greatly enhances related to identification. He can identify his family members.
  • Identify similar objects.
  • Response to the action and verbal nods of adults.
  • Explore things and try to learn things.
  • Understand the instructions given by adults.
  • Able to arrange and assemble things like playing with building blocks, making a line of cars, etc.
  • They perceive things properly. If you play their favorite poem or song they will quickly run to the LED to watch that.
  • They have a clear idea about object permanence. therefore they cry when you take something from their hands and look here and there. They try to find that object immediately. 

Language Development From Baby Talk to Complete Sentence

As the physical changes in infancy happen, brain development is also in the process. As the newborn come into this world he possessed minimal abilities. But every infant shows their ability to communicate according to their own capacity. Still, there are some communication milestones that would be discussed below. When the brain develops, infants also showability to produce different sounds and communicate.

Sometimes parents need to identify common infant reflexes of communication. Such as facial expressions and eye contact, etc. On the other hand for communication infants take information through hearing and by sight. They also focus on words from adults and try to repeat them. All this process helps infants to learn a proper language for communication. This process is also called developmental communication.  

Producing sounds

A six to eight-month-old infant can easily do babbling. Babbling is the combination of consonants and vowels. They produce sounds like baba, dada, mama, etc. Infants actually do not know the meaning of these sounds but they keep on repeating them. These sounds are actually known as babbling. 

One word plus Gestures

Nine to 18 months old infants can speak a single word. Sometimes followed by gestures. For example, they can say NO and use head movement as a gesture. They can say CAT and point with their fingers as a gesture.

One Sentence

An 18-24 months infant can speak two words. For instance, (see the cow) and (give milk). A 24-30-month-old infant can speak and repeat sentences. He can easily convey his messages and demands. You can support language development by talking a lot with your child, and responding when your child communicates.

Social/Emotional Development From Shyness To Empathy

The social development of an infant refers to his ability to experience, express, and control emotions. Infants are social creatures. They are born with the ability to express their feelings. Within the first week, they start expressing comfort when their caregivers are around. It is considered that infant vision is very strong. They move their heads to the direction where the caregiver moves. They produce different sounds and start cooing when they are comfortable.   

Most of the families report that by the end of three months their infant smiles to all the family members. This gesture shows that now the infant knows its family members. While looking after an infant if you interact with them they give expressions. They also try to understand and respond in their own rhymes. It is their inborn ability or social-emotional skill.

Social Emotional Milestones

0-2 months

If we talk about social-emotional milestones then 0-2 months is so important. This is the time period when an infant seeks self-awareness. They try to build relationships, feel love, and security and be nurtured.

6-9 months

6-9 months infants are so adventurous. This is the major change occurring era related to social-emotional development. Six months old infants try to approach those things which attract them. They reach there by crawling or rolling. During this era, infants try to explore new things. They express their likes and dislikes. Especially related to food. They quickly eat those things which they like and tease a lot while eating things and taste they don’t like


9-18 months old infants become well aware of society. They show comfort and express happiness with their known persons. They feel shy and hesitate to express emotions in the presence of strangers. This is also known as stranger anxiety.

2 years

A 2 years old infant is capable of understanding, expressing, and managing his emotions. This is the time when we can teach them with the help of punishment and reward. Two years old infants can feel guilty over their mistakes. They are capable of showing empathy. They know their favorite dresses and take care of their belongings.  

sudden infant death syndrome

The first year after birth is so difficult for the parents. Because parents have to understand the newborn’s world and the newborn does not know anything about this world. He can convert his mouth with a blanket by mistake. Or he can chock on saliva and can vomit during sleep. All these things can become a major cause of sudden infant death syndrome.

Sudden infant death syndrome is a syndrome in which an infant dies during sleep or while laying in bed. The actual cause of SIDS always remains unexplained. So the parents need to be extra alert for the infant’s security.


It is very exciting to feel and observe all the physical changes in infancy. An infant is a blessing by nature. To nurture them is a full-time job. Every infant shows development in his own style and pattern. Still, there are some standard milestones that every infant has to cover.

Otherwise, parents need to see experts eradicate the fear of any abnormality and for disease control. After infancy, parents need to appreciate independence, and patience and they must learn the ways how to make a baby an obedient being. 

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About The Author

Qurratulain Nabeel

This is QURRATULAIN - an M.Phil in Applied Psychology. Being a mother of two I tried to put my knowledge into practice, which proved very beneficial for me. By using the platform of I am so pleased to share my experience with people all around the world.

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