Child Development and Early Learning

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Highest Quality Ingredients Zahler's Prenatal contains a balanced synergistic formula that provides a curated compilation of nutrients your developoing baby requires, in the optimal ratios of absorption, metabolism and safety. Remember that toddlers have small stomachs, so they need to eat small amounts of food frequently throughout the day. From Wikipedia, the free encyclopedia. Longitudinal analysis with linked population data. Medecine clinique et experimentale. Indian Journal of Medical Research. For instance, they may have behavioral problems and might be antisocial.


Frequently Asked Questions About Brain Development

Vygotsky felt that development was a process and saw periods of crisis in child development during which there was a qualitative transformation in the child's mental functioning. Attachment theory, originating in the work of John Bowlby and developed by Mary Ainsworth , is a psychological , evolutionary and ethological theory that provides a descriptive and explanatory framework for understanding interpersonal relationships between human beings.

Erikson , a follower of Freud's, synthesized both Freud's and his own theories to create what is known as the "psychosocial" stages of human development, which span from birth to death, and focuses on "tasks" at each stage that must be accomplished to successfully navigate life's challenges.

Erikson's eight stages consist of the following: With this process, Watson believed that all individual differences in behavior were due to different learning experiences. This experiment had shown that phobia could be created by classical conditioning. Skinner further extended this model to cover operant conditioning and verbal behavior. Furthermore, he used reinforcement and punishment to shape in desired behavior.

In accordance with his view that the sexual drive is a basic human motivation, [ citation needed ] Sigmund Freud developed a psychosexual theory of human development from infancy onward, divided into five stages. The use of dynamical systems theory as a framework for the consideration of development began in the early s and has continued into the present century.

Another useful concept for developmentalists is the attractor state, a condition such as teething or stranger anxiety that helps to determine apparently unrelated behaviors as well as related ones.

Dynamic systems theory also relates to the concept of the transactional process, [24] a mutually interactive process in which children and parents simultaneously influence each other, producing developmental change in both over time. The "core knowledge perspective" is an evolutionary theory in child development that proposes "infants begin life with innate, special-purpose knowledge systems referred to as core domains of thought" [25] There are five core domains of thought, each of which is crucial for survival, which simultaneously prepare us to develop key aspects of early cognition; they are: Although the identification of developmental milestones is of interest to researchers and to children's caregivers, many aspects of developmental change are continuous and do not display noticeable milestones of change.

When developmental change is discontinuous, however, researchers may identify not only milestones of development, but related age periods often called stages.

A stage is a period of time, often associated with a known chronological age range, during which a behavior or physical characteristic is qualitatively different from what it is at other ages.

When an age period is referred to as a stage, the term implies not only this qualitative difference, but also a predictable sequence of developmental events, such that each stage is both preceded and followed by specific other periods associated with characteristic behavioral or physical qualities. Stages of development may overlap or be associated with specific other aspects of development, such as speech or movement.

Even within a particular developmental area, transition into a stage may not mean that the previous stage is completely finished. For example, in Erikson's discussion of stages of personality, this theorist suggests that a lifetime is spent in reworking issues that were originally characteristic of a childhood stage. Although developmental change runs parallel with chronological age, [30] age itself cannot cause development. Environmental factors affecting development may include both diet and disease exposure, as well as social, emotional, and cognitive experiences.

Rather than acting as independent mechanisms, genetic and environmental factors often interact to cause developmental change. One kind of environmental guidance of development has been described as experience-dependent plasticity, in which behavior is altered as a result of learning from the environment.

Plasticity of this type can occur throughout the lifespan and may involve many kinds of behavior, including some emotional reactions. In addition to the existence of plasticity in some aspects of development, genetic-environmental correlations may function in several ways to determine the mature characteristics of the individual. Genetic-environmental correlations are circumstances in which genetic factors make certain experiences more likely to occur. In all of these cases, it becomes difficult to know whether child characteristics were shaped by genetic factors, by experiences, or by a combination of the two.

Empirical research that attempts to answer these questions may follow a number of patterns. Initially, observational research in naturalistic conditions may be needed to develop a narrative describing and defining an aspect of developmental change, such as changes in reflex reactions in the first year.

Such studies examine the characteristics of children at different ages. Some child development studies examine the effects of experience or heredity by comparing characteristics of different groups of children in a necessarily non-randomized design. Milestones are changes in specific physical and mental abilities such as walking and understanding language that mark the end of one developmental period and the beginning of another. Studies of the accomplishment of many developmental tasks have established typical chronological ages associated with developmental milestones.

However, there is considerable variation in the achievement of milestones, even between children with developmental trajectories within the typical range. Some milestones are more variable than others; for example, receptive speech indicators do not show much variation among children with typical hearing, but expressive speech milestones can be quite variable.

A common concern in child development is developmental delay involving a delay in an age-specific ability for important developmental milestones. Prevention of and early intervention in developmental delay are significant topics in the study of child development. An example of a milestone would be eye-hand coordination, which includes a child's increasing ability to manipulate objects in a coordinated manner.

Increased knowledge of age-specific milestones allows parents and others to keep track of appropriate development. There is a phenomenal growth or exponential increase of child development from the age of 4 to 15 years old especially during the age of 4 to 7 years old based on the Yamana chart [40].

The Heckman's chart shows that the highest return of investment in education is maximum during the early years age 1 to 3 years old and decreases to a plateau during the school-aged years and adolescence. Child development is not a matter of a single topic, but progresses somewhat differently for different aspects of the individual.

Here are descriptions of the development of a number of physical and mental characteristics. Physical growth in stature and weight occurs over the 15—20 years following birth, as the individual changes from the average weight of 3. As stature and weight increase, the individual's proportions also change, from the relatively large head and small torso and limbs of the neonate , to the adult's relatively small head and long torso and limbs. The speed of physical growth is rapid in the months after birth, then slows, so birth weight is doubled in the first four months, tripled by age 12 months, but not quadrupled until 24 months.

At birth, head size is already relatively near to that of an adult, but the lower parts of the body are much smaller than adult size. In the course of development, then, the head grows relatively little, and torso and limbs undergo a great deal of growth.

Genetic factors play a major role in determining the growth rate, and particularly the changes in proportion characteristic of early human development.

However, genetic factors can produce the maximum growth only if environmental conditions are adequate. Poor nutrition and frequent injury and disease can reduce the individual's adult stature, but the best environment cannot cause growth to a greater stature than is determined by heredity.

Individual differences in height and weight during childhood are considerable. Some of these differences are due to family genetic factors, others to environmental factors, but at some points in development they may be strongly influenced by individual differences in reproductive maturation. The American Association of Clinical Endocrinologists defines short stature as height more than 2 standard deviations below the mean for age and gender, which corresponds to the shortest 2.

Abilities for physical movement change through childhood from the largely reflexive unlearned, involuntary movement patterns of the young infant to the highly skilled voluntary movements characteristic of later childhood and adolescence. The speed of motor development is rapid in early life, as many of the reflexes of the newborn alter or disappear within the first year, and slows later.

Like physical growth, motor development shows predictable patterns of cephalocaudal head to foot and proximodistal torso to extremities development, with movements at the head and in the more central areas coming under control before those of the lower part of the body or the hands and feet.

Types of movement develop in stage-like sequences; [46] for example, locomotion at 6—8 months involves creeping on all fours, then proceeds to pulling to stand, "cruising" while holding on to an object, walking while holding an adult's hand, and finally walking independently.

The mechanisms involved in motor development involve some genetic components that determine the physical size of body parts at a given age, as well as aspects of muscle and bone strength. The dorsolateral frontal cortex is responsible for strategic processing. The parietal cortex is important in controlling perceptual-motor integration and the basal ganglia and supplementary motor cortex are responsible for motor sequences.

Intra-limb correlations, like the strong relationship and distance between hip and knee joints, were studied and proved to affect the way an infant will walk. There are also bigger genetic factors like the tendency to use the left or right side of the body more, predicting the dominant hand early. Sample t-tests proved that there was a significant difference between both sides at 18 weeks for girls and the right side was considered to be more dominant Piek et al.

Some factors, like the fact that boys tend to have larger and longer arms are biological constraints that we cannot control, yet have an influence for example, on when an infant will reach sufficiently. Overall, there are sociological factors and genetic factors that influence motor development.

Nutrition and exercise also determine strength and therefore the ease and accuracy with which a body part can be moved. This is significant in motor development because the hind portion of the frontal lobe is known to control motor functions. This form of development is known as "Portional Development" and explains why motor functions develop relatively quickly during typical childhood development, while logic, which is controlled by the middle and front portions of the frontal lobe, usually will not develop until late childhood and early adolescence.

Skilled voluntary movements such as passing objects from hand to hand develop as a result of practice and learning. This promotes participation and active learning in children, which according to Piaget's theory of cognitive development is extremely important in early childhood rule. Typical individual differences in motor ability are common and depend in part on the child's weight and build.

Infants with smaller, slimmer, and more maturely proportionated infants tended to belly crawl and crawl earlier than the infants with larger builds.

Infants with more motor experience have been shown to belly crawl and crawl sooner. Not all infants go through the stages of belly crawling.

However, those who skip the stage of belly crawling are not as proficient in their ability to crawl on their hands and knees. Atypical motor development such as persistent primitive reflexis beyond 4—6 months or delayed walking may be an indication of developmental delays or conditions such as autism , cerebral palsy , or down syndrome.

Children with Down syndrome or Developmental coordination disorder are late to reach major motor skills milestones. A few examples of these milestones are sucking, grasping, rolling, sitting up and walking, talking. Children with Down syndrome sometimes have heart problems, frequent ear infections , hypotonia , or undeveloped muscle mass.

This syndrome is caused by atypical chromosomal development. Along with Down syndrome, children can also be diagnosed with a learning disability. Learning Disabilities include disabilities in any of the areas related to language, reading, and mathematics. Regardless of the culture a baby is born into, they are born with a few core domains of knowledge. These principals allow him or her to make sense of their environment and learn upon previous experience by using motor skills such as grasping or crawling.

There are some population differences in motor development, with girls showing some advantages in small muscle usage, including articulation of sounds with lips and tongue. Cognitive development is primarily concerned with ways in which young children acquire, develop, and use internal mental capabilities such as problem solving , memory , and language.

The capacity to learn , remember , and symbolise information , and to solve problems , exists at a simple level in young infants, who can perform cognitive tasks such as discriminating animate and inanimate beings or recognizing small numbers of objects. Cognitive development has genetic and other biological mechanisms, as is seen in the many genetic causes of intellectual disability. The ability to learn temporal patterns in sequenced actions was investigated in elementary-school age children.

Temporal learning depends upon a process of integrating timing patterns with action sequences. Children ages 6—13 and young adults performed a serial response time task in which a response and a timing sequence were presented repeatedly in a phase-matched manner, allowing for integrative learning.

The degree of integrative learning was measured as the slowing in performance that resulted when phase-shifting the sequences. Learning was similar for the children and adults on average but increased with age for the children.

Finally, WCST performance and response speed predicted temporal learning. Taken together, the results indicate that temporal learning continues to develop in pre-adolescents and that maturing executive function or processing speed may play an important role in acquiring temporal patterns in sequenced actions and the development of this ability.

There are typical individual differences in the ages at which specific cognitive abilities are achieved, [ citation needed ] but schooling for children in industrialized countries is based on the assumption that these differences are not large.

There are few population differences in cognitive development. Newborn infants do not seem to experience fear or have preferences for contact with any specific people. In the first few months they only experience happiness, sadness, and anger. Separation anxiety is a typical stage of development to an extent. Kicking, screaming, and throwing temper tantrums are perfectly typical symptoms for separation anxiety.

Depending on the level of intensity, one may determine whether or not a child has separation anxiety disorder. This is when a child constantly refuses to separate from the parent, but in an intense manner.

This can be given special treatment but the parent usually cannot do anything about the situation. The capacity for empathy and the understanding of social rules begin in the preschool period and continue to develop into adulthood. Some aspects of social-emotional development, [ citation needed ] like empathy, [ citation needed ] develop gradually, but others, like fearfulness, [ citation needed ] seem to involve a rather sudden reorganization of the child's experience of emotion.

Genetic factors appear to regulate some social-emotional developments that occur at predictable ages, such as fearfulness, and attachment to familiar people. Experience plays a role in determining which people are familiar, which social rules are obeyed, and how anger is expressed. Parenting practices have been shown to predict children's emotional intelligence. The objective is to study the time mothers and children spent together in joint activity, the types of activities that they develop when they are together, and the relation that those activities have with the children's trait emotional intelligence.

Correlations between time variables and trait emotional intelligence dimensions were computed using Pearson's Product-Moment Correlation Coefficient. Partial correlations between the same variables controlling for responsive parenting were also computed. The amount of time mothers spent with their children and the quality of their interactions are important in terms of children's trait emotional intelligence, not only because those times of joint activity reflect a more positive parenting, but because they are likely to promote modeling, reinforcement, shared attention, and social cooperation.

Population differences may occur in older children, if, for example, they have learned that it is appropriate for boys to express emotion or behave differently from girls, [ citation needed ] or if customs learned by children of one ethnic group are different from those learned in another. Language serves the purpose of communication to express oneself through a systematic and traditional use of sounds, signs, or written symbols. They include phonology, lexicon, morphology and syntax, and pragmatics.

This happens in three stages. First, each word means an entire sentence. This stage occurs around age two or three. Third, around age seven or eight, words have adult-like definitions and their meanings are more complete.

A child learns the syntax of their language when they are able to join words together into sentences and understand multiple-word sentences said by other people. This stage usually occurs between 12 and 18 months of age. Second, between 18 months to two years, there is the modification stage where children communicate relationships by modifying a topic word. The third stage, between two and three years old, involves the child using complete subject-predicate structures to communicate relationships.

Fourth, children make changes on basic sentence structure that enables them to communicate more complex relationships. This stage occurs between the ages of two and a half years to four years. The fifth stage of categorization involves children aged three and a half to seven years refining their sentences with more purposeful word choice that reflects their complex system of categorizing word types. Finally, children use structures of language that involve more complicate syntactic relationships between the ages of five years old to ten years old.

Infants begin with cooing and soft vowel sounds. Shortly after birth, this system is developed as the infants begin to understand that their noises, or non-verbal communication, lead to a response from their caregiver. Eventually, they are able to add pronouns to words and combine them to form short sentences. By age 1, the child is able to say 1—2 words, responds to its name, imitates familiar sounds and can follow simple instructions. This skill develops close to their second birthdays.

Vocabulary typically grows from about 20 words at 18 months to around words at 21 months. Children's recorded monologues give insight into the development of the process of organizing information into meaningful units.

By three years the child begins to use complex sentences, including relative clauses, although still perfecting various linguistic systems. For this, the child needs to learn to combine his perspective with that of others and with outside events and learn to use linguistic indicators to show he is doing this. They also learn to adjust their language depending on to whom they are speaking. Although the role of adult discourse is important in facilitating the child's learning, there is considerable disagreement among theorists about the extent to which children's early meanings and expressive words arise.

Findings about the initial mapping of new words, the ability to decontextualize words, and refine meaning of words are diverse. In this model, parental input has a critical role but the children ultimately rely on cognitive processing to establish subsequent use of words. There is no single accepted theory of language acquisition. Instead, there are current theories that help to explain theories of language, theories of cognition, and theories of development. They include the generativist theory, social interactionist theory , usage-based theory Tomasello , connectionist theory, and behaviorist theory Skinner.

Generativist theories refer to Universal Grammar being innate where language experience activates innate knowledge. This theory states that children acquire language because they want to communicate with others; this theory is heavily based on social-cognitive abilities that drive the language acquisition process.

Communication can be defined as the exchange and negotiation of information between two or more individuals through verbal and nonverbal symbols, oral and written or visual modes, and the production and comprehension processes of communication. All questions in a conversation should be answered, comments should be understood or acknowledged and any form of direction should, in theory, be followed.

In the case of young, undeveloped children, these conversations are expected to be basic or redundant. These four components of communication competence include: Language development is viewed as a motive to communication, and the communicative function of language in-turn provides the motive for language development. As they begin to acquire more language, body movements take on a different role and begin to complement the verbal message. This gesture includes communicative pointing where an infant points to request something, or to point to provide information.

Language acquisition and development contribute to the verbal form of communication. Children originate with a linguistic system where words they learn, are the words used for functional meaning. According to this, children view words as a means of social construction, and that words are used to connect the understanding of communicative intentions of the speaker who speaks a new word.

Another function of communication through language is pragmatic development. Mechanics of verbal interaction include taking turns, initiating topics, repairing miscommunication, and responding to lengthen or sustain dialogue. This shift in balance of conversation suggests a narrative discourse development in communication. Delays in language is the most frequent type of developmental delay. According to demographics 1 out of 5 children will learn to talk or use words later than other children their age.

Some children will also display behavioral problems due to their frustration of not being able to express what they want or need. Simple speech delays are usually temporary. Most cases are solved on their own or with a little extra attribution from the family. In certain circumstances, parents will have to seek professional help, such as a speech therapist. It is important to take into considerations that sometimes delays can be a warning sign of more serious conditions that could include auditory processing disorders , hearing loss , developmental verbal dyspraxia , developmental delay in other areas, or even an autism spectrum disorder ASD.

There are many environmental causes that are linked to language delays and they include situations such as, the child is having their full attention on other skills, such as walking perfectly, rather than on language. Another circumstance could be a child that is in a daycare that provides few adults to be able to administer individual attention.

Perhaps the most obvious component would be a child that suffers from psychosocial deprivation such as poverty, malnutrition, poor housing, neglect, inadequate linguistic stimulation, or emotional stress. Language delay can be caused by a substantial amount of underlying disorders, such as intellectual disability. Intellectual disability takes part for more than 50 percent of language delays. Language delay is usually more rigorous than other developmental delays in intellectually disabled children, and it is usually the first obvious symptom of intellectual disability.

Intellectual disability accounts to global language delay, including delayed auditory comprehension and use of gestures. Impaired hearing is one of the most common causes of language delay. A child who can not hear or process speech in a clear and consistent manner will have a language delay. Even the most minimum hearing impairment or auditory processing deficit can considerably affect language development. Essentially, the more the severe the impairment, the more serious the language delay.

Nevertheless, deaf children that are born to families who use sign language develop infant babble and use a fully expressive sign language at the same pace as hearing children. Developmental Dyslexia is a developmental reading disorder that occurs when the brain does not properly recognize and process the graphic symbols chosen by society to represent the sounds of speech.

Children with dyslexia may encounter problems in rhyming and separating sounds that compose words. These abilities are essential in learning to read. Early reading skills rely heavily on word recognition. When using an alphabet writing system this involves in having the ability to separate out the sounds in words and be able to match them with letter and groups of letters.

Because they have trouble in connecting sounds of language to the letter of words, this may result difficulty in understanding sentences. They have confusion in mistaking letters such as "b" and "d". For the most part, symptoms of dyslexia may include, difficulty in determining the meaning of a simple sentence, learning to recognize written words, and difficulty in rhyming. Autism and speech delay are usually correlated. Problems with verbal language are the most common signs seen in autism.

Early diagnosis and treatment of autism can significantly help the child improve their speech skills. Autism is recognized as one of the five pervasive developmental disorders, distinguished by problems with language, speech, communication and social skills that present in early childhood.

Some common autistic syndromes are the following, being limited to no verbal speech, echolalia or repeating words out of context, problems responding to verbal instruction and may ignore others who speak directly. Malnutrition, maternal depression and maternal substance abuse are three of these factors which have received particular attention by researchers, however, many more factors have been considered.

Although there are a large number of studies contemplating the effect of maternal depression and postnatal depression of various areas of infant development, they are yet to come to a consensus regarding the true effects. There are numerous studies indicating impaired development, and equally, there are many proclaiming no effect of depression on development.

However, the authors conclude that it may be that short term depression has no effect, where as long term depression could cause more serious problems. A further longitudinal study spanning 7 years again indicate no effect of maternal depression on cognitive development as a whole, however it found a gender difference in that boys are more susceptible to cognitive developmental issues when their mothers suffer depression.

Infants with chronically depressed mothers showed significantly lower scores on the motor and mental scales within the Bayley Scales of Infant Development, [85] contrasting with many older studies. The use of cocaine by pregnant women is not the only drug that can have a negative effect on the fetus. Smoking tobacco increases pregnancy complications including low birth rate, prematurity, placental abruption, and intrauterine death.

It can also cause disturbed maternal-infant interaction; reduced IQ, ADHD, and it can especially cause tobacco use in the child. Parental marijuana exposure may have long-term emotional and behavioral consequences. A ten-year-old child who had been exposed to the drug during pregnancy reported more depressive symptoms than fetuses unexposed. Some short-term effects include executive function impairment, reading difficulty, and delayed state regulation. An opiate drug, such as heroin, decreases birth weight, birth length, and head circumference when exposed to the fetus.

Children suffering malnutrition in Colombia weighed less than those living in upper class conditions at the age of 36 months The effect of low iron levels on cognitive development and IQ is a subject still to reach consensus. Socioeconomic status is measured primarily based on the factors of income, educational attainment and occupation. Children in families who experience persistent financial hardships and poverty have significantly impaired cognitive abilities compared to those in families who do not face this issue.

Mother's employment is associated with slightly lower test scores, regardless of socioeconomic status. However, those whose working mother is of a higher socioeconomic status experience more disadvantages because they are being removed from a more enriching environment than a child care.

Obviously, the quality of child care is a factor to be considered. Low income children tend to be cared for by grandparents or extended family [] and therefore form strong bonds with family. High income children tend to be cared for in a child care setting or in home care such as a nanny. If the mother is highly educated, this can be a disadvantage to the child. Even with quality of care controlled for, studies still found a negative correlation between full-time work within the first year and child development.

Effects are felt more strongly when women resume full-time work within the first year of the child's life. Low-income families are less likely to provide a stimulating home learning environment to their children due to time constraints and financial stress. Upper-income families are able to afford learning opportunities inside and outside of the classroom.

Diarrhea caused by the parasitic disease Giardiasis is associated with lower IQ. Harboring of this parasite could adverse several health implications in children affecting childhood development and morbidity. Reducing the prevalence of the parasite can be a benefit in child growth, development, and educational outcome.

High levels of lead in the blood is associated with attention deficits, [] while arsenic poisoning has a negative effect on verbal and full Intelligence Quotient IQ. Organophosphates have been specifically linked to poorer working memory , verbal comprehension, perceptual reasoning and processing speed.

A major problem in childhood is obesity. In America, the number of obese children is rapidly increasing. In human pregnancy , prenatal development, also known as antenatal development , is the development of the embryo following fertilization, and continued as fetal development.

By the end of the tenth week of gestational age the embryo has acquired its basic form and is referred to as a fetus. The next period is that of fetal development where many organs become fully developed. This fetal period is described both topically by organ and chronologically by time with major occurrences being listed by gestational age.

In other animals the very early stages of embryogenesis are the same as those in humans. In later stages, development across all taxa of animals and the length of gestation vary. Different terms are used to describe prenatal development , meaning development before birth. The perinatal period from Greek peri , "about, around" and Latin nasci "to be born" is "around the time of birth ". In developed countries and at facilities where expert neonatal care is available, it is considered from 22 completed weeks usually about days of gestation the time when birth weight is normally g to 7 completed days after birth.

When semen is released into the vagina , the spermatozoa travel through the cervix and body of the uterus and into the Fallopian tubes. Fertilization of the egg cell ovum , usually takes place in one of the Fallopian tubes. Many sperm are released with the possibility of just one sperm cell managing to adhere to and enter the thick protective shell-like layer surrounding the ovum.

The first sperm that penetrates fully into the egg donates its genetic material DNA. The egg then polarizes, repelling any additional sperm. The resulting combination is called a zygote , a new and genetically unique organism. The term "conception" refers variably to either fertilization or to formation of the conceptus after its implantation in the uterus, and this terminology is controversial.

Prior to fertilization, each ovum, as a gamete , contains half of the genetic material that will fuse with the male gamete, which carries the other half of the genetic material DNA. The ovum only carries the X female sex chromosome whilst the sperm carries a single sex chromosome of either an X or a male Y chromosome. The resulting human zygote is similar to the majority of somatic cells because it contains two copies of the genome in a diploid set of chromosomes.

One set of chromosomes came from the nucleus of the ovum and the second set from the nucleus of the sperm. The zygote is male if the egg is fertilized by a sperm that carries a Y chromosome, and it is female if the egg is fertilized by a sperm that carries an X chromosome. In contrast, the mitochondrial genetic information of the zygote comes entirely from the mother via the ovum. The embryonic period in humans begins at fertilization penetration of the egg by the sperm and continues until the end of the 10th week of gestation 8th week by embryonic age.

The period of two weeks from fertilization is also referred to as the germinal stage. The embryo spends the next few days traveling down the Fallopian tube. It starts out as a single cell zygote and then divides several times to form a ball of cells called a morula. Further cellular division is accompanied by the formation of a small cavity between the cells. This stage is called a blastocyst. Up to this point there is no growth in the overall size of the embryo, as it is confined within a glycoprotein shell, known as the zona pellucida.

Instead, each division produces successively smaller cells. The blastocyst reaches the uterus at roughly the fifth day after fertilization. It is here that lysis of the zona pellucida occurs. This process is analogous to zona hatching , a term that refers to the emergence of the blastocyst from the zona pellucida, when incubated in vitro.

This allows the trophectoderm cells of the blastocyst to come into contact with, and adhere to, the endometrial cells of the uterus. The trophectoderm will eventually give rise to extra-embryonic structures, such as the placenta and the membranes. The embryo becomes embedded in the endometrium in a process called implantation.

In most successful pregnancies, the embryo implants 8 to 10 days after ovulation. Rapid growth occurs and the embryo's main features begin to take form. This process is called differentiation , which produces the varied cell types such as blood cells, kidney cells, and nerve cells. A spontaneous abortion, or miscarriage , in the first trimester of pregnancy is usually [7] due to major genetic mistakes or abnormalities in the developing embryo. During this critical period most of the first trimester , the developing embryo is also susceptible to toxic exposures, such as:.

From the 10th week of gestation 8th week of development , the developing organism is called a fetus. Since the precursors of all the major organs are created by this time, the fetal period is described both by organ and by a list of changes by weeks of gestational age.

Because the precursors of the organs are now formed, the fetus is not as sensitive to damage from environmental exposure as the embryo was. Instead, toxic exposure often causes physiological abnormalities or minor congenital malformation. Development continues throughout the life of the embryo and fetus and through into life after birth.

Significant changes occur to many systems in the period after birth as they adapt to life outside the uterus. Fetal hematopoiesis first takes place in the yolk sac. The function is transferred to liver by 10th week of gestation and to spleen and bone marrow beyond that. Fetus produces megaloblastic red blood cells early in development, which become normoblastic near term.

Life span of fetal RBCs is 80 days. Rh antigen appears at about 40 days of gestation. Fetus starts producing leukocytes at 2 months gestation mainly from thymus and spleen. Lymphocytes derived from thymus are called T lymphocytes , whereas the ones derived from bone marrow are called B lymphocytes.

Both these populations of lymphocytes have short-lived and long-lived groups. Short-lived T lymphocytes usually reside in thymus, bone marrow and spleen; whereas long-lived T lymphocytes reside in blood stream. Plasma cells are derived from B lymphocytes and their life in fetal blood is 0.

Thyroid gland is the first to develop in fetus at 4th week of gestation. Insulin secretion in fetus starts around 12th week of gestation. The fetus passes through 3 phases of acquisition of nutrition from mother: Growth rate of fetus is linear up to 37 weeks of gestation, after which it plateaus. A baby born within the normal range of weight for that gestational age is known as appropriate for gestational age AGA.

An abnormally slow growth rate results in the infant being small for gestational age , and, on the other hand, an abnormally large growth rate results in the infant being large for gestational age. A slow growth rate and preterm birth are the two factors that can cause a low birth weight.

The growth rate can be roughly correlated with the fundal height which can be estimated by abdominal palpation. More exact measurements can be performed with obstetric ultrasonography. Intrauterine growth restriction is one of the causes of low birth weight associated with over half of neonatal deaths. Poverty has been linked to poor prenatal care and has been an influence on prenatal development.

Women in poverty are more likely to have children at a younger age, which results in low birth weight. Many of these expecting mothers have little education and are therefore less aware of the risks of smoking , drinking alcohol , and drug use — other factors that influence the growth rate of a fetus. Women between the ages of 16 and 35 have a healthier environment for a fetus than women under 16 or over Women over 35 are more inclined to have a longer labor period, which could potentially result in death of the mother or fetus.

Women under 16 and over 35 have a higher risk of preterm labor premature baby , and this risk increases for women in poverty, African Americans, and women who smoke.

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