Unit 2: Ages and stages of development (Birth to Childhood)

2.1  Prenatal (conception to birth)

2.2  Infancy (Birth to 2 year)

2.3  Toddler (2 to 4 years)

2.4  Early childhood (Up to 7 years)

2.5  Late childhood (7 to 14 years)












2.1         Prenatal (conception to birth)


The sperm and ovum that unite to form new individual are uniquely suited for the task of reproduction. The ovum is a tiny sphere, measuring 1/175 inch in diameter that is barely visible to the naked eyes as a dot size of the period at the end of this sentence. But in its microscopic world, it is a giant- the largest cell in the human body. The ovum’s size makes it a perfect target for the much smaller sperm, which measure only 1/500 inch.




The male produce sperm in vast number-an average pf 300 million a day.in the final process of maturation ,each sperm develops a tail that permits it to swim long distances, upstream in the female reproductive tract, through  the cervix(opening of the uterus), and into the fallopian tube , where fertilisation usually takes place. The journey is difficult, and many sperm die. Only 300 to 500 reach the ovum ,if one happens to be present. Sperm live for up to 6 days and can lie in wait for the ovum, which survives for only 1 day after being realised into the fallopian tube. However most conceptions result from intercourse during a 3-day period –on the day of ovulation or during the 2 days preceding it.


1.     Period Of  The Zygote


The period of the zygote lasts about two weeks, from fertilisation until the tiny mass of cell drifts down and out of the fallopian tube and attaches its self to the wall of uterus. The zygote’s first cell duplication is long and drawn out; it is not complete until about 30 hours after conception. Gradually.  New cell added at a faster rate. By the fourth day, 60 to 70 cells exist that form a hallow ,fluid-filled ball called a blastocyst. The cell on the inside of the blastocyst, called the embryonic disk, will become the new organism; the thin outer ring of cells, termed the trophoblast, will become the structures that provide protective covering and nourishment.

Implantation: Between the seventh and ninth days, implantation occurs. Blastocyst invades into uterine wall and becomes implanted in it (implantation)

The Placenta and Umbilical Cord: The placenta permits food and oxygen to reach the developing organism and waste product to be carried away. Membrane forms that allows these substance to be exchanged but  prevents the mother’s and the embryo’s blood form mixing directly. The placenta is connected to the developing organism by the umbilical cord, which first appears as a primitive body stalk and, during the course of pregnancy, grows to a length of 1 to 3 feet.

By the end of the period of the zygote, the developing organisms has found food and shelter in the uterus.


2.     Period of the Embryo

The period of the embryo lasts from implantation through the eighth week of pregnancy. During these brief six weeks, the most rapid prenatal changes take place, as the groundwork is laid for all body structures and internal organs. Because all parts of the body are forming.


Image result for ectoderm mesoderm endoderm

Last Half of the First Month: In the first week of this period, the embryonic disk forms three layers of cells: (1) the ectoderm, which will become the nervous system and skin; (2) the mesoderm, from which will develop the muscles, skeleton, circulatory system, and other internal organs; and (3) the endoderm, which will become the digestive system, lungs, urinary tract, and glands. These three layers give rise to all parts of the body.

The Second Month: In the second month, growth continues rapidly. The eyes, ears, nose, jaw, and neck form. Tiny buds become arms, legs, fingers and toes. Internal organs are more distinct: The intestines grow, the heart develops separate chambers, and the liver.

At 7 weeks, production of neurons(nerve cells that store and transmit information) begins deep inside the neural tube at the astounding pace of more than 250,000 per minute (Nelson, 2011)

At the end of this period, the embryo – about 1 inch long and 1/7 ounce in weight- can already sense its world. It responds to touch, particularly in the mouth area and the soles of the feet.


3.     Period of the Fetus

The period of the fetus, from the ninth week to the end of pregnancy, is the longest prenatal period. During the growth and finishing phase the organism increases rapidly in size especially from the ninth to twentieth week.

The Third Month: In the third month the organs muscles and nervous system start to become organized and connected when the brain signals the fetus kicks bends its arm forms fist curls its toes, turn its head , open its mouth, and even suck its thumb , stretched and yawn.

The tiny lungs begin to expand and contract in an early rehearsalof breathing movement by the twelfth week, the external genitals are well-formed ,and the sex of the fetus can be detected with ultrasound. Other finishing touch appear as fingernail, toenail, tooth, buds and eyelids. The heart beat can now be heard through a stethoscope.

Prenatal development is sometime divided into trimesters or three equal time period. At the end of third month, the first trimester is complete.

The Second Trimester: By the middle of the second trimester , between 17 and 20 week, the new being has grown large that the ,mother can feel its movement. A white cheese like substance called vernix covers the skin protecting it from chapping during the long month spent in the amniotic fluid.

White downy hair called lanugo also covers the entire body helping the vernix stick to the skin. At the end of second trimester, many organs are well developed. Also, most of the brain’s billion of neurons are in place. Few will be produce after this time .consequently brain weight increases.

Brain growth means new behavioral capacities. The 20 week-old fetus can be stimulated as well as irritated by sound. Slow eye movement appear with rapid eye movement following at 22 week. Still, a fetus born at this time cannot survive. Its lungs are too immature, and the brain cannot yet control breathing movements or body temperature.

The Third Trimester: During the final trimester, a fetus born early has a chance of survive. The point, at which the baby can first survive, called the age of viability, occurs sometime between 22-26 week. A baby born between the seventh and eighth month, however usually needs oxygen assistance to breathe.

Although the brain’s respiratory centre is now mature tiny air sacs in the lunges are not yet ready to inflate and exchange carbon dioxide for oxygen.

Around 28 weeks fetus blink there eyes in reaction to nearby sounds. 

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By the end of the pregnancy, the fetus takes on the beginnings of a personality. Higher fetal activity in the last week of pregnancy predicts a more active in fact in the first month of life.

Fetal activity level an indicator of healthy neurological development which fosters adaptability in childhood.






Length & Weight

Major events





The one-celled zygote multiplies and forms a blastocyst.





The blastocyst burrows into the uterine lining structure that feed and protect the developing organism begin to form-amnion, chorion, yolk, sac, placenta, and umbilical cord




¼ inch (6mm)

A primitive brain and spinal cord appear. Heart , muscles, ribs, backbone, and digestive tract begin to develop




1 inch (2.5cm);

½  ounce


Many external body structures (face, arms, legs, toes, finger) and internal organs form. Production of neurons begins. The sense of touch emerges, and the embryo can move.




3 inches (7.6cm);

Less than 1 ounce


Rapid increase in size begins. Nervous system, organs, and muscles become organized and connected and new behavioral capacities (kicking, thumb sucking, mouth opening, and rehearsal of breathing) appear. The fetus’s sex is evident.




12 inches (30cm);

1.8 pounds


The fetus continues to enlarge rapidly. In the middle of the period, the mother can feel fetal movements. Vernix and lanugo keep the fetus’s skin from chapping in the amniotic fluid. Most of the brain’s neurons are in place by 24 weeks. Eyes are sensitive to light, and the fetus reacts to sound.




20 inches (50cm);

7.5 pounds


The fetus has a good chance of survival if born during this time. Size increases, Lungs mature. Rapid brain development causes sensory and behavioral capacities to expand. Antibodies are transmitted from mother to fetus to protect against disease. Most fetuses rotate into an upside-down position in preparation for birth.



2.2         Infancy (Birth to 2 year)


Infancy comprises the first year of life. This is a period of rapid growth in most bodily systems and dimensions and rapid development of the neuromuscular system.  

After birth, the growth is oriented towards functional state of life. Growth is mainly by addition of more cells or increase in the protoplasm. It can be said that anabolic processes exceed catabolic processes and there is increase in size, shape and weight. This characterizes the infant stage.  

Immediately after birth the rate of growth increases. In case weight the peak velocity is reached at two months after birth. The cells become larger in size. The cervical and lumber curvatures of the spinal column appear as the baby begins to straighten the head and tries to sit up and to stand. During infancy growth is very rapid. More than 50 percent of birth length and 200 percent of birth weight take place during the first year of life.

The neonatal period

The neonatal period (birth to 1 month) is a time of extensive and ongoing system transition from uterine environment to external world; this includes the initial period after birth which is referred to as the perinatal period.

Neonates and sleep

·      Sleeping more in this time than they will throughout lifespan

·      Neonate spends the majority (approximately 2/3 of time) sleeping (16 hours) -> this declines throughout rest of life to about 20%

Neonates and crying

·      Neonates spend about 2 hours per day crying -> increases after birth until 6 weeks

·      Mostly non-communicative until they're older, but can also be due to hunger, discomfort, pain, or overstimulation

·      Peaks in late afternoon and evening

Physical development

Sensory and motor skills development:

Newborns have all five senses. Your newborn quickly learns to recognize your face, the sound of your voice, and how you smell. Your newborn's sense of touch is especially developed, particularly around the mouth. Your baby also has a strong sense of smell. After a few days, your newborn hears fairly well and responds most noticeably to high-pitched and loud sounds. Your baby recognizes and prefers sweet tastes to those that are sour, bitter, or salty. Vision is developing quickly but is believed to be the weakest of the senses. Motor skills develop as your baby's muscles and nerves work together. Movements are mostly controlled by reflexes, such as the rooting reflex, which is when a newborn's head turns and his or her mouth "reaches" toward a touch. Hands are tightly fisted when the baby is alert.

Developmental psychologists used the term infancy to denote the period of development that generally is from birth to two years of age. The word infant means “without language”. Infancy includes development in the areas of cognition, perception, motor activity, emotion, sociability and language. In the beginning of infancy period infants can recognise human faces and after that they can differentiate between known and unknown faces and react differently. Development on different areas take place through infancy to toddlerhood, i.e, the first three years of life.

Physical development:

It refers to the changes in the body. This development is rapid during infancy. Infants increase their body weight almost triple and increase in height by about one-third during the first year alone. Not only body size and weight of the infant increase but also brain size expands rapidly during the first 18 months and brain weight of the infant reaching more than half of the adult brain due to rapid growth of dendrites and axons within the brain and glia cells. Physical development also includes development in vision, hearing, perceptual development etc. Infants motor development takes place in a sequential order and this type of development proceeds from head towards the limbs. Infant first controls his head and trunk, then lift his chest, sit upright, crawling, creeping, stand with help, stand along with holding some objects, walking and so on. This development occurs due to improvement of skills and control of other body parts like legs, arms, etc. Gradually children develop their eye, head and hand coordination and are able to pick up things.

Piaget noted that the sensory motor stage of cognitive development occurs during infancy. During infancy period there are development in vision, control of muscles and nervous system, start to eat and sleep on regular intervals, sit on their own and to hold objects themselves.

Social and Emotional Development:

Infants at about two months old demonstrate social smiling in response to human faces. When they are four months old, they show laughter and express anger, sadness and surprise by six months. By 8 or 10 months, they actively seek information about other people‟s feelings. They learn to respond when somebody calls them by their names at about age six to twelve months. They also have face to face contact. They are afraid of when their parents or care-taker leaves them. They start expressing anger if their needs are not met. Thus, social and emotional development starts during the period of infancy to toddlerhood itself Children start expressing their feelings of trust, fear, confidence, love, etc. They express affection as a form of emotion to others as a part of social emotional development.. If a child is neglected during this period, it affects his social emotional development negatively. During this period as children are attached with their care givers, parents and other siblings, etc., so children develop separation anxiety if they are separated from them. This appears at the age of nine months.

Cognitive Development

Infants express their intellect by making various sounds like gurgling, cooing, etc. They observe their own hands and feet. They gradually learn the relationship between their actions and the external world. They can manipulate various objects to produce effects. Infants seem to acquire knowledge about the world only through motor activities and sensory impressions. They try to focus their eyes on various objects and people, put everything in their mouth. Children develop ability to form mental representation during infancy. Around the end of the 9th month infants demonstrate object permanence. By babyhood stage they learn to make sounds like mama, papa, they try to copy various activities as others do. By 12 months of age many children are able to say some words which can be understood by others. During infancy children start developing language ability, learn through their sense organs and explore the world in their own ways. In this period children are dependent on others where as in toddlerhood stage, creativity and socialisation begins. In infancy period emotions are of simple type but in toddlerhood emotions are of varying types and growth is faster than other periods of life.



2.3         Toddler (2 to 4 years)


During the toddler years, your child will continue change dramatically in the following five main areas of development: physical, cognitive, emotional and social, language, and sensory and motor skills.

Physical Development

While children tend to gain about three to five pounds and grow three to five inches between ages one and two, this rapid growth tends to slow down between ages two and five. During this time, your child will develop increasing strength and coordination.   

Cognitive Development

After beginning to recognize familiar people and objects, between the age of one and two, your toddler will be better able to recall recent events. During this age your child will imitate others and will become much more imaginative, especially during play time. From two to five, the ability to think and understand grows greatly as children learn letters, numbers, symbols and colors.

Emotional and Social Development

The competing emotions that develop during this age are often behind the “terrible twos” label. From 12 to 24 months, children continue to develop strong bonds with their loved ones, while at the same time wanting to be more independent. Between ages two and four, your child will likely begin to like to “do it myself” and will want to make more choices on his or her own. 

From age two to five, children learn more about their feelings and begin developing friendships with other children their age. Children begin to understand the difference between right and wrong at this age. They will look to their parents for limits and rules and will also often test these limits.  Often, when children this age do something wrong, they will begin to feel guilty about it.

Language Development

Understanding progresses faster than speech in a toddler’s language development. Between 15 to 18 months, most toddlers know 10 times more words than they can verbally communicate. By the age of two, however, vocabularies can span between 50 and 100 words and children begin using two or more words in combination. By the age of five, children can use thousands of words to communicate and will speak in sentences.

Sensory and Motor Development

Improving motor skills make your child more mobile by age two. The toddler years are a time when your child will likely be in constant motion. Toddlers will quickly master walking and move on to running, jumping and climbing. Around age two, most toddlers will be able to navigate stairs, kick or throw a ball and draw simple lines. During this time, children may still stumble frequently and be accident prone. By age five, better control of fine motor skills allows children to dress and undress themselves (a necessity for toilet training) and write some letters.   



2.4         Early childhood (Up to 7 years)


Childhood ordinarily spans from the end of infancy (the first birthday) to the start of adolescence. The infant attains childhood before reaching adolescence. It is often divided into early childhood and middle childhood.

·      The early childhood (2-6 years):  is the period of eruption of milk teeth. Motor skills are refined, language develops, ties are formed with peers, and the child learns through play.

·      The middle childhood (7 to 11 years) is the period of eruption of permanent teeth, though not all erupt. These are the school years when the child acquires literacy skills, thought processes are refined, friendships emerge and self-concept is formed.

Early childhood is a time of tremendous growth across all areas of development. The dependent newborn grows into a young person who can take care of his or her own body and interact effectively with others. For these reasons, the primary developmental task of this stage is skill development.

Physically, between birth and age three a child typically doubles in height and quadruples in weight. Bodily proportions also shift, so that the infant, whose head accounts for almost one-fourth of total body length, becomes a toddler with a more balanced, adult-like appearance. Despite these rapid physical changes, the typical three-year-old has mastered many skills, including sitting, walking, toilet training, using a spoon, scribbling, and sufficient hand-eye coordination to catch and throw a ball.

Between three and five years of age, children continue to grow rapidly and begin to develop fine-motor skills. By age five most children demonstrate fairly good control of pencils, crayons, and scissors. Gross motor accomplishments may include the ability to skip and balance on one foot. Physical growth slows down between five and eight years of age, while body proportions and motor skills become more refined.
Physical changes in early childhood are accompanied by rapid changes in the child's cognitive and language development. From the moment they are born, children use all their senses to attend to their environment, and they begin to develop a sense of cause and effect from their actions and the responses of caregivers.

Over the first three years of life, children develop a spoken vocabulary of between 300 and 1,000 words, and they are able to use language to learn about and describe the world around them. By age five, a child's vocabulary will grow to approximately 1,500 words. Five-year-olds are also able to produce five-to seven-word sentences, learn to use the past tense, and tell familiar stories using pictures as cues.
Language is a powerful tool to enhance cognitive development. Using language allows the child to communicate with others and solve problems. By age eight, children are able to demonstrate some basic understanding of less concrete concepts, including time and money. However, the eight-yearold still reasons in concrete ways and has difficulty understanding abstract ideas.

A key moment in early childhood socioemotional development occurs around one year of age. This is the time when attachment formation becomes critical. Attachment theory suggests that individual differences in later life functioning and personality are shaped by a child's early experiences with their caregivers. The quality of emotional attachment, or lack of attachment, formed early in life may serve as a model for later relationships.

From ages three to five, growth in socioemotional skills includes the formation of peer relationships, gender identification, and the development of a sense of right and wrong. Taking the perspective of another individual is difficult for young children, and events are often interpreted in all-or-nothing terms, with the impact on the child being the fore-most concern. For example, at age five a child may expect others to share their possessions freely but still be extremely possessive of a favorite toy. This creates no conflict of conscience, because fairness is determined relative to the child's own interests. Between ages five and eight, children enter into a broader peer context and develop enduring friendships. Social comparison is heightened at this time, and taking other people's perspective begins to play a role in how children relate to people, including peers.

Physical Development:

Early childhood stage covers the age range from 3 to 6 years. Children begin to develop athletic appearance and they lose their babyish roundness. As abdominal muscles develop, the trunk, arms and legs grow longer. Their brain and head grow rapidly than any other parts of the body.

Psycho-Social Development:

In early childhood stage children can say full sentences, express their feelings and emotions and communicate their needs and feelings and emotions and communicate their needs and feelings with others. During early childhood children have better control of their physical movement and can have better coordination of their body parts. They also learn how to cooperate with other children and conflict resolution when they are about the age of five or six years they are independent in various ways. There are three important socio-emotional developments, such as; development of self, gender roles and moral development, take place during childhood period. Through the process of identification the child comes to know who he is and differentiates from who he wants to be. The child is aware of this process through his observation and imitation of parents and significant others. The child‟s personality is laid down by this identification. The child learns the socially appropriate behaviours by observing and participating in the social events. When the children are about the age of 5 to 6 years they can understand that they belong to a particular gender and also learn to behave gender roles.

Cognitive Development:

The childhood period is important for cognitive development of children. Children are curious to know the answers of questions like, “why”, “Where” and “How” for everything that happens. Cognitive abilities include memory, reasoning, perception, problem solving and thinking abilities which continue to emerge throughout childhood. Jean Piaget worked on childhood cognitive development. He concluded that children are not less intelligent than adults but they simply think differently. Piaget explained that human beings acquire knowledge through interaction with the environment in which he lives in, Piaget named early child hood (2 to 7 years) as the preoperational stage of cognitive development which there is a great expansion in the use of symbolic thought, or representational ability. But they are not able to use logic. In this stage children do not need to be in sensory motor contact with an object, person or event in order to think about it. They are aware that superficial alternations do not change the nature of things and also understand the cause-effect relationship. They develop the ability to classify objects, people and events. Children can count and deal with quantities. They become more able to imagine how others might feel and aware of mental activity and the functioning of the mind.



2.5         Late childhood (7 to 14 years)


Historically, middle childhood has not been considered an important stage in human development. Sigmund Freud's psychoanalytic theory labeled this period of life the latency stage, a time when sexual and aggressive urges are repressed. Freud suggested that no significant contributions to personality development were made during this period. However, more recent theorists have recognized the importance of middle childhood for the development of cognitive skills, personality, motivation, and inter-personal relationships. During middle childhood children learn the values of their societies. Thus, the primary developmental task of middle childhood could be called integration, both in terms of development within the individual and of the individual within the social context.

Perhaps supporting the image of middle childhood as a latency stage, physical development during middle childhood is less dramatic than in early childhood or adolescence. Growth is slow and steady until the onset of puberty, when individuals begin to develop at a much quicker pace. The age at which individuals enter puberty varies, but there is evidence of a secular trend–the age at which puberty begins has been decreasing over time. In some individuals, puberty may start as early as age eight or nine. Onset of puberty differs across gender and begins earlier in females.

As with physical development, the cognitive development of middle childhood is slow and steady. Children in this stage are building upon skills gained in early childhood and preparing for the next phase of their cognitive development. Children's reasoning is very rule based. Children are learning skills such as classification and forming hypotheses. While they are cognitively more mature now than a few years ago, children in this stage still require concrete, hands-on learning activities. Middle childhood is a time when children can gain enthusiasm for learning and work, for achievement can become a motivating factor as children work toward building competence and self-esteem.

Middle childhood is also a time when children develop competence in interpersonal and social relationships. Children have a growing peer orientation, yet they are strongly influenced by their family. The social skills learned through peer and family relationships, and children's increasing ability to participate in meaningful interpersonal communication, provide a necessary foundation for the challenges of adolescence. Best friends are important at this age, and the skills gained in these relationships may provide the building blocks for healthy adult relationships.

Adolescence (11-20 years): This period is marked by puberty which signals the onset of rapid physical and hormonal changes, emergence of abstract thinking, sexual maturity, stronger peer ties, sense of self and autonomy from parental control. During this period there is a marked acceleration of growth which is known as adolescence growth spurt. The adolescence spurt is a constant phenomenon and occurs in all children, though it varies in intensity and duration from one child to another. In boys it takes place, on the average from age 12 to 15. In girls the spurt begins about two years earlier than in boys. Differentiation in primary and secondary sexual characteristics marks the adolescence period. There are changes in the reproductive organs, in body size and shape, in the relative proportions of muscle, fat and bone and in a variety of physiological functions.

The term adolescence is derived from the Latin word adolescere, which means to sprout into maturity. It is the intermediate period between childhood and adulthood. This period is otherwise called as the age of teenagers. It includes three sub periods, such as: early adolescence (12 yrs -14 yrs), middle adolescence (14 yrs -17 yrs) and late adolescence (17 yrs -19 yrs). Adolescence is the developmental transition between childhood and adulthood entailing major physical, cognitive and psychological changes. During this period physical changes that occur are universal, but social and psychological changes largely depend on the cultural contexts. As this is the transitional phase of life adolescents rebel against their parents and society most often. Therefore, this period is labelled as storm and stress period.

Physical Development

Sexuality and identity formation are two major challenges of the period of adolescence. During this period the most rapid physical growth occurs. There are changes in the growth rate, sexual characteristics, and behaviour. Adolescent boys and girls develop in their height, weight, strength and development of bones, muscles, etc. Puberty and sexual maturity for both boys and girls marks the beginning of the adolescent period. Growth spurts and development of secondary sex characteristics signal about the onset of adolescence. Menstruration is the first sign of puberty for girl whereas appearance of few whiskers is the sign of puberty for boys. The approximate age for sexual maturation is 12.5 years for boys and 10.5 years for girls. Puberty begins in response to changes in the hormonal system. Sex hormones like testosterone in males and estrogen in females are secreted from the sex glands. The secretion of sex hormones help in pubertal development and also closely associated with emotions. During this period emotion like aggression is found in boys and depression is marked in girls. They try to imitate their idols. Girls are conscious about their shapes and do what their friends do while boys try to go for body building.

Psycho-Social Development

During this period the physical changes in adolescents bring about a wide variety of psychological changes. Adolescents become innovative and take interest in learning various skills with great interest. They feel that no one understands them, and they often consider themselves to be „superman‟. Their sense of uniqueness is expressed in the form of personal fable around them away from the world of reality. They are argumentative and they have a tendency to find fault with the authority figures. They do not able to differentiate between ideal and real. Adolescents are very self-conscious and it is expressed in the concept of imagery audiences. These imaginary audiences criticise, encourage and motivate an adolescent. Peer group influence is very important during adolescence. They want to do what their friends are doing, Adolescents abuse alcohol and drugs under peer pressure. Developmental psychologists viewed that adolescence as a period of risk, turmoil, uncertainty and conflict, if proper care is not taken during this period children became antisocial, abusive or depressed.

Cognitive Development

During adolescence not only there are changes in body structures occur but also they think differently from younger children. Jean Piaget opined that adolescents enter the highest level of cognitive development, i.e. formal operational stage of cognitive development. During this period adolescents thoughts change from concrete objects to abstract events. They can think flexibly enough about the world. They accumulate knowledge through interaction and apply the learned concepts to new tasks. Teenagers develop their reasoning skills and engage in hypothetical deductive reasoning. As adolescents develop their logical thinking, they are becoming aggressive and argumentative. They are able to understand abstract concepts such as congruence and mass and they think in terms of theoretical concepts. They are conscious about others opinion regarding them and curious enough to know about spirituality, traditions and beliefs. Thus, during adolescence people deal with problems on an abstract level, to form hypothesis and to reason from proposition that are contrary to fact.