CHAPTER 3

• Epigenetic principle (Erik Erikson)


  • Stage cycles are characterised by events or crises that must be satisfactorily resolved in order for development to proceed smoothly
  • If such crises are not resolved within a given life period, the all subsequent stages reflect that failure in the form of physical, cognitive, social or emotional maladjustment
• Prenatal period


  Begins with a single cell at conception and ends with a newborn baby
• Prenatal period was viewed as simply one of growth and maturation, a time during which the body and organs were formed
• Maturation


  Aspects of development under genetic control
• Development was considered as proceeding largely under genetic control and immune to external influences
• Currently due to technology in examining the fetus, it is clear that genetic factors alone are not the only factors that determine growth. Environmental factors also play a role.
• Culture


  Plays a significant influence over people's thoughts, feelings and behaviours, as well as over how they define health, growth, births and life cycles
• African culture


  People have a strong connection with their ancestors, especially with regards to families, marriages and births
• Developmental stages characterised by crises

  • May be interpreted as a sign of ancestors turning their backs on the pregnant woman and her family
  • The reason behind this can be interpreted as failure to perform the traditional practices
• Nature versus nurture debate

  How much is development during the prenatal period determined by genes and how much by the environment?
• Traditionally, the prenatal period has been viewed as largely under the control of genes that direct the physical growth of the individual
• However, environmental influences contribute more to development than was previously thought
• Development during the prenatal period is an interaction between genes and environment
• Physical development


  • There are many cultural myths about the beginning of life and origin of children
  • Some parents find it difficult to tell their children about where children come from
• Cultural myths about the origin of children

  • Babies are delivered by aeroplane
• It was, and can still be, embarrassing for some parents to tell their children the truth about their formation and the birth process
• Germinal period


  1. First stage of the prenatal period; starts with fertilisation of the egg by the sperm and ends with the establishment of the pregnancy

  2. At ovulation, a mature egg is released from the ovary and enters the fallopian tube

  3. Sperm travel up the tube to meet the egg, and fertilisation takes place in the fallopian tube

  4. The process can however go wrong and cause ectopic pregnancy

  5. In the case of identical twins, triplets and other multiple births, the zygote divides into two or more separate entities after the ovum has been fertilised by the sperm

  6. Each of the developing organisms has the same genetic material, and children should therefore be identical in those characteristics determined by genetic factors
• Embryonic period


  1. Begins during the middle of the second week and concludes at the end of the eighth week

  2. Major organs of the body begin to form

  3. Specialisation time: when cells divide and differentiate to form specific organs, for example the heart and lungs

  4. Mysteries of development: how cells 'know' to become a heart or lung cell, given that they are all identical at the start of the differentiation process

  5. Beginning of the third month the embryo is called a fetus

  6. Umbilical cord is the 'lifeline' that connects the embryo to the placenta

  7. Oxygen and nutrients from the mother pass through the umbilical cord to the embryo

  8. The placenta is a structure that grows on the inner wall of the uterus and supplies the oxygen and nourishment to the embryo. It also removes embryonic waste
• Fetal period


  1. Fetus is an unborn offspring, from the embryo stage

  2. Development and differentiation of structures emerge during the embryonic period

  3. The connection is formed between the nervous system and the muscles, with the result that spontaneous movement of the arms and legs occurs

  4. Fourth month - the face of the fetus becomes more human. The body lengthens so that the head is no longer out of proportion to the body

  5. The mother is able to feel the movements of the fetus - stronger during fifth month

  6. Sixth month - eyes are fully formed and they look about in all directions

  7. Seventh month is boundary between survival or not outside the uterus

  8. Eighth month - fatty tissue is formed beneath the fetus's skin to protect it against the temperature change that will occur at birth

  9. Antibodies are transferred from the mother to the child in order to reduce the risk of the child catching disease

  10. Change of position- the head is situated in a downward position in preparation for the birth process
• Principles that guide prenatal development


  • Development proceeds in a cephalocaudal direction (from head to foot)
  • Development proceeds from the basic to the more specialised: Organs first develop their basic characteristics, and then detail is added as development proceeds
  • Development proceeds in order of importance: Development begins with the 'more important' organs for survival, and the less important ones develop later
• Brain development


  1. Brain begins its development at 18 days after fertilisation

  2. It is one of the slowest organs to develop, with development continuing for many years after birth

  3. The relative proportion of brain to body decreases as development proceeds

  4. Brain develops from a layer of cells from the embryonic disc, the neural plate

  5. This plate folds to form the neural tube, which closes, beginning in the middle and progressing to each end

  6. The neural tube is fully closed by the end of the fourth week. Failure to close properly may lead to defects such as spina bifida
• Gross level of brain development

  Considers how the neural tube develops to form the main structures of the brain, hindbrain, midbrain, and forebrain
• Micro level of brain development

  Examines how the complex organisation of cells within the brain is achieved
• Gene abnormalities


  • The result of faulty genes
  • Faulty genes may convey distorted messages
  • Examples are sex-linked abnormalities such as haemophilia, and ethnically linked gene abnormalities
  • Ethnically linked gene abnormalities are abnormalities that have a higher frequency among certain ethnic groups, because one of the progenitor (origin/ancestral) parents of a particular ethnic group had a faulty gene
  • The faulty gene is therefore transmitted from generation to generation
  • The first affected individual in a family who brings a genetic disorder to the attention of the medical community is termed the proband
  • For a genetic illness, first-degree relatives (mother, father, siblings) are more likely to have the disorder of the proband than are more distant relatives
• Chromosomal abnormalities

  • In 40 per cent of abortion patients, the cause of the abortion is a chromosomal defect
  • Most common manifestation of chromosomal abnormality is Down's syndrome
  • Down's syndrome is characterised by mental retardation, particular facial characteristics, a stocky physique and a pleasant nature
  • In more than 90 per cent of such cases, the condition arises as a result of the presence of an extra chromosome at the twenty-first pair - hence the name trisomy-21 being given to the most common form of the syndrome
  • Such a person has 47 chromosomes
• Teratogens


  Substances that exert an adverse influence on development
• Teratology


  The study of adverse consequences of exposure to environmental agents
• Teratogenic effects are caused by substances external to the embryonic or fetal environment, for example alcohol through maternal drinking
• Teratogenic effects are also caused by deficiencies of substances, for example vitamin deficiencies and other dietary deficiencies such as malnutrition
• During pregnancy, an illness will generally not affect the unborn child, because the viruses and bacteria cannot enter the placenta
• In some cases, however, viruses and bacteria are so small that they are able to enter the placenta. This will affect the unborn child
• Rubella (German measles)


  Maternal rubella during the first trimester has been associated with severe mental retardation, deafness, and microcephaly in 50 per cent of infants born to those mothers
• Pregnant mothers should have access to the vaccine at clinics to develop immunity to rubella
• AIDS (acquired immune deficiency syndrome)

  • Mother-to-child transmission takes place often
  • More than 90 per cent of mother-to-child transmission of HIV infection takes place during pregnancy, labour, delivery or breastfeeding
  • Without any intervention, between 15 and 45 per cent of infants born to mothers living with HIV will become infected
  • During the birth process when the umbilical cord separates from the placenta, it results in an exchange of blood between the mother and child
• Syphilis


  • Syphilis can lead to miscarriages, stillbirths, or death of the baby after birth
  • Syphilitic infection of the fetus usually takes place only after four or five months. Early treatment can prevent fetal infection
  • The incidence of syphilis in Western countries is less than 1 per cent, whereas in Africa it is between 1 and 17 per cent (depending on the geographical area), with an average of about 4 per cent in sub-Saharan Africa
• Genital herpes


  • Genital herpes is an infection that is usually transmitted during sexual contact - through the skin and nervous system
  • It causes sores on the sexual organs. The virus can penetrate the placenta and infect the fetus
  • Most infections occur during the birth process when the baby comes into contact with the mother's birth canal
• Effects of drugs


  • Drugs such as heroin, morphine and tik cause physical dependency
  • A child born to a mother who uses such drugs during pregnancy may experience withdrawal symptoms, such as respiratory problems and convulsions shortly after birth and may die
  • Such withdrawal symptoms arise because the baby's regular supply of the drug from the mother is cut off when he or she is born
• Fetal alcohol syndrome


  • The symptoms of FAS include a small head, an abnormal facial appearance, growth retardation, learning disabilities, and behavioural disorders
  • Alcohol exhibits what is called a dose-dependent effect: the greater the exposure, the greater the effect on the fetus
  • Teratogenic effects are not simply the result of environmental exposure
  • In some cases the effect(s) is a result of an interaction between the individual's genes and the environmental agent, e.g. not all women who drink the same amount of alcohol during pregnancy will have babies with identical syndromes
• Fetal tobacco syndrome


  • It is a syndrome in children born to mothers who smoke five or more cigarettes daily during pregnancy
  • Can cause retarded growth in babies and may later negatively affect cognitive performance
  • Nicotine penetrates the placenta and blocks the supply of oxygen to the fetus
  • Nicotine can be found in the milk of mothers who smoke and can cause restlessness in babies and an unpleasant taste in the milk
• Effects of nutrition on the fetus

  • Fetus is directly dependent on the mother for its nutritional needs
  • The baby obtains nutrition from the mother's bloodstream via the placenta
  • Common nutrition-related abnormalities: higher risk of stillbirth, low birth weight, premature births, deformities, retarded growth, and death during the first year of life
  • Malnutrition can affect the child's brain and, subsequently, cognitive development, and it can lead to retardation
  • Other obstacles are increased susceptibility to bacterial, viral, and parasitic diseases - probably the result of impaired immunological function
  • Poor nutritional status lead to changes in rate of growth