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Human Growth and Development

Written by Simran Johal

Prenatal development is the process in which we see a baby undergo a process of growth and development within the womb fertilization until birth. There are three main stages in prenatal development: Germinal Stage, Embryonic Stage and the Fetal Stage. Let’s look into the Germinal Stage. 

    The way a plant seed germinates in soil, a sperm cell germinates amongst an egg. During this stage, the organism begins cell division and growth. It’s about 14 days in length and lasts from conception to the implantation of the zygote. The zygote is the fancy way of saying a fertilized egg. Differentiation of the cells begins to occur. This is when all the cells necessary for the placenta, umbilical etc. will begin to differentiate from the embryo. It estimates that about 60% of natural conceptions fail to implant in the uterus. 

    The Embryonic Stage is a process required in order to create an embryo. It begins once an organism is implanted in the uterine wall and stays attached until birth. It lasts from the third week to the eighth week of prenatal development after the initial conception. During this stage, cells will continue differentiating and at roughly 22 days after impregnation, the brain begins to slightly form (in the form of tubes) which is the very first step of brain development, and also the spinal column where cells enclose the spinal cord and the fluid surrounding it. There are two major directions in which growth occurs for the Embryonic Stage. The first being Cephalocaudal Development. This is where a gradual change in the head size to the body size occurs. Then the second, which is when, the muscular controls of the arms relative to the hands and fingers grow. The head develops in the fourth week, during this stage, and a pulse begins. In the early stages of Embryonic development, gills and tails are apparent (due to evolution). In this stage, the mother doesn’t usually know that she is pregnant. It’s during this period that the major structures of the body are beginning to form. The embryo is approximately 1 inch long in length and weighs about 4 grams at the end of this period. The embryo can move and respond to touch at this time. A rough sequence of development during the Germinal stage is as follows.

    During week three, the heart, brain, blood cells, spinal cord, circulatory system and digestive system begin to form. During week 4, the arm and leg buds (limbs), facial structures and bones begin to develop. The heart continues to develop. As does the brain and nervous tissue. The heart begins to beat. During week 5, the eyes, kidney nose, lungs continue to develop. The heart, brain, nervous tissue and digestive tract begin development. During the sixth week, digits, feet and hands begin to develop. The brain, heart and circulatory systems keep on developing. In the seventh week, hair follicles, nipples and sex organs begin to develop. In the eighth, and final week of the Embryonic Stage, facial features become more distinct, internal organs become well-developed, the brain can signal for muscles to move, hear development is completed and sex organs begin to form outside the body. Next, we move to the fetal stage. 

    The fetal stage begins at the ninth week and continues until birth. This is where the organism is referred to as a fetus. Majors structures are beginning to develop and by the twelfth week, the fetus has all its body parts )including external genitalia). In the following weeks, the fetus will develop hair, nails, teeth and the excretory and digestive systems will continue to develop. At the end of the week 12, the fetus weighs roughly 28 grams and is roughly 3 inches. A rough sequence of development during the Fetal stage is as follows.

    From weeks 9-12, the fetus is roughly 8cm in length and we can see the beginnings of teeth start to appear. Features such as the face, neck, eyelids, limbs, digits, and genitals are well formed. The beginnings of teeth appear, and red blood cells begin to produce in the liver. The fetus is able to make a tiny fist. During weeks 13-15, the fetus reaches roughly 25cm in length. Super fine hair begins to develop on the head, we see structures such as the lungs, sweat glands, muscles, and bones continue to develop, the fetus is able to swallow. At weeks 16-20, the fetus reaches roughly 20cm in length. Fine hair begins to cover all skin surfaces and fat begins to develop under the skin. Features such as fingers and toenails, eyebrows and eyelashes appear. The fetus becomes more active, and the mother can sometimes begin to feel kicks at this stage. From the weeks 21-24, the fetus reaches roughly 28.5 cm in length and begins to weigh approximately 0.7 kg. Hair grows longer on the head, the eyebrows and eyelashes finish forming. The lungs continue to extensively develop and the eyes finish developing. In the weeks 25-28, The fetus approaches roughly 38cm in length and weighs approximately 1.2kg. The next few weeks mark a period of rapid brain and nervous system development. The fetus gains control of other movements (opening and closing eyelids). The lungs have developed significantly so that the air breathing is possible. Weeks 29-32, the fetus reaches roughly 38/43 cm in length and weighs approximately 2kg. Under the skin, fat becomes more defined. The lungs remain immature but breathing movements do begin. The fetus’s bones are developed but have not yet hardened. In the weeks 33-36, the fetus reaches roughly 41/48cm in length and weighs 2.6-3.0kg. Body fat continues to increase under the skin. Fine hair begins to disappear, and fingernails are fully grown. The fetus has gained a high amount of control over body functions. Finally, from weeks 36-38, the fetus approaches, 48-53 in length. The first fine hair all over the body has mostly disappeared and is replaced with thicker hair on the head. Fingernails have grown past the tips of the fingers. In a healthy fetus, all organ systems are functioning. 

    There are indeed mental health issues that can occur prior to birth. Schizophrenia is thought to be genetic, consequently it occurs in our genetic makeup before we’re born. People whose mothers were undernourished while pregnant had a significantly increased risk of major affective disorders, such as mania and depression; sometimes severe enough to require hospitalization. Exposure to stress during pregnancy can cause things like autism, depressions. Anxiety and mood disorders. 

    Infancy and Toddlerhood is the type of growth occurring in children from the ages of zero to thirty-six, this includes emotional, behavioural,physical and mental growth. Culture, environment socioeconomic status or genetic factors can influence things such as when a child will begin to walk, crawl or talk. In the early 20th century, child development scholars began to understand that children weren’t just childre but actual individuals with their own unique personalities and distinct needs. The majority of infants are alert and beginning to act just hours after a normal birth, even though their body systems are immature. The sense of smell and taste are also evidently established. Infants/Toddlers will turn away from unpleasant smells and sometimes express a preference for sweet tastes as opposed to something that is more bitter tasting. Between two and three months, newborn reflexes begin to disappear. They cry less and begin to engage in social smiling. Infants entertain themselves with their own features (fingers and toes). At four months old, vision improves, infants pay attention to bright objects, preferring primary colours (particularly red). One study showed that infants were shown both symmetrical and asymmetrical faces expressed a preference for the symmetry of faces that have been identified as “attractive” by adults. However, between the ages of five and eight months, infant preferences were for asymmetrical faces. 

    Parents’ relationships with their children play a vital role in the mental health of infants and toddlers. Indications of mental health issues amongst infants or toddlers could be visible through their problems with sleeping and/or feeding or, if they over-respond or under-respond to the things around them. It can be difficult to diagnose an infant because you can’t explicitly tell what they feel or think. Normal development looks different in children, how do you know if your child’s behaviour is anything that should cause concern? A doctor can work to see what else may be causing or adding to the infant’s problems. This can take a long time, but it’s important as a diagnosis will help connect with treatment options and take actions early. 

    During early childhood, healthy development provides good building blocks for educational achievement, productivity, and helps them become a responsible ordinary citizen in their community and successful parenting of their children. During early childhood, children need nutrition, protection and stimulation for successful and healthy brain development. The earliest years are when babies’ brains form new connections. Poverty is such an important and common factor as to whether or not children receive the stimulation and nutrition they need. “250 million children under five in low-and middle-income countries risk not reaching their development potential because of extreme poverty and stunting.” The most disadvantaged children are less likely to have access to the things needed for a healthy development, for example, neglect and abuse, extreme stress: these kinds of things can block a healthy development. There is minimal public understanding of the importance of a child’s first years and little demand for policies, programs and funding. Here are some of the key facts regarding human growth and development in early childhood. 

    Lack of nutrition in early childhood leads to stunting, which globally affects nearly one-in-four children younger than five. Risks associated with poverty – such as undernutrition and poor sanitation – can lead to developmental delays and a lack of progress in school. Silent discipline is widespread in many countries, and nearly 7% of children between two and four were yelled at or screamed at in the past month. 300 million children younger than five have been exposed to societal violence. For a child in a low, or middle, income country, poor early development could mean they earn around one-quarter less in income, as an adult. For a country, poor and early childhood development could mean economic loss; in India, the loss is about twice the gross domestic product spent on health. 

    So what’s the solution to all of this? Interventions at the right time can sushion all of this development, break intergenerational cycles of inequity and provide a fair start in life. For babies born into poverty or deprivation, intervening early can reverse harm because that is when the brain is developing rapidly. 

    By middle childhood, children can dress themselves, play games such as catch and potentially, hopefully, tie their own shoes etc. It is important to make sure that children have independence from family becomes more important as children are brought into contact with the larger world. At this time, physical, social and mental skills develop quickly and thus, friendships become more important. It is eally important for children to develop confidence in all areas of life. Children might start to think more about the future and understand more about their place in the world. They’ll pay more attention to things such as friendship and want to be liked and accepted by friends. They also learn better ways to describe experiences and talk about thoughts and feelings, they become more empathetic and show more concern for others. 

    What should parents be doing when their child is approaching middle childhood? They can do things such as; showing more affection for your children, recognizing their accomplishments, help your child develop a sense of responsibility (i.e. chores), talk to your child about school, friends and the things he or she looks forward to in the near or far future, help them set achievable goals, make clear rules and stick to them (be clear about what behaviour is okay and not okay), do fun things as a family, get involved with their school, continue reading to them, use discipline to guide and protect your child rather than punishment to lower their self esteem, praise your child for good behaviour, support your child taking on new challenges and encourage your child to join school and community groups, such as a team sports, or to take advantage of volunteer opportunities, children in this age group might start to form stronger “more complex friendships and peer relationships. It becomes more emotionally important to have friends, especially of the same sex”. Please do keep in mind that many children cognitively and physically developing may experience mental health disorders such as depression, anxiety, ADHD, OCD, eating disorders and, you should be careful as to how you approach certain situations with your child as you may have no idea what they’re going through. 

    During adolescence, children begin to develop the capacity for abstract and logical thought. They have an enhanced awareness of themselves and ability to reflect empathetically onto their actions. Self awareness often turns into self consciousness and for adolescents, there is potentially a preoccupation with physical appearance, attractiveness and a heightened sensitivity to differences from peers: not always but sometimes. Right and wrongs for adolescents is fixed and absolute. Older adolescents, often question standards of behaviour and may reject traditions. The people in this age group find schoolwork that is more complex, they’re able to identify areas of interest as well as relative strengths and weaknesses. This is a period of time in which many people in this age group begin to consider career options. Many adolescents begin to engage in risky behaviours such as fast driving, experimenting sexually, risky sexual practices, illegal activities, theft, alcohol and drug use. 

    The areas of the brain that control emotions develop and mature. Although adolescents, do learn to gradually control/suppress inappropriate thoughts and actions and replace them with goal-oriented behaviours. The emotional aspect of this growth is often very trying, often with the patience of parents, teachers and other adults/authoritarians. Communication, even within stable families, can be difficult and is worsened when families are divided or parents have emotional problems of their own. 

    Family is at the center of social life for children. During the time period of adolescence, the peer group begins to replace the family as the child’s primary social focus. Peer groups are often established because of distinctions in dress, appearance, attitudes, hobbies. Adolescents who find themselves without a peer group may develop intense feelings of being different and alienated. Gang membership is more common when the home and social environment are unable to counterbalance the dysfunctional demands of peer groups. 

    Doctors should screen all adolescents for mental health disorders such as: depression, bipolar disorder, anxiety, schizophrenia, eating disorders, anorexia nervosa and bulimia nervosa. Substance abuse typically begins during adolescence, this isn’t to marginalize anyone, it is simply a statistic. More than 70% of adolescents in the United States try alcohol before they graduate high school. Somes statistics show that adolescents who start drinking alcohol at a young age are more likely to develop an alcohol disorder as an adult. For example, adolescents who start drinking at age 13 are 5 times more likely to develop an alcohol use disorder than those who start drinking at 21. Almost 50% of US adolescents try cigarettes, over 40% try electronic cigarettes, and more than 40% try marijuana while they are in high school. Use of other drugs is much less common, although misuse of prescription drugs, including drugs for pain and stimulants, is on the rise.

Our psychological and physical development go hand in hand and for one to thrive or even survive the other must do the same. We need to take care of ourselves as well as we do physically, mentally and vice versa. Be a support system for loved ones.

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