Prenatal development&birth 3


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Prenatal development&birth 3

  1. 1. Lecture 3 Prenatal Development & Birth Ching-fen Hsu 2013/10/4
  2. 2. Growth After Conception • From a zygote • Dramatic change in size • Consist 2 billion cells & weigh 7 pounds • Study of prenatal development seeks to explain how changes in form, size, & behaviour take place • Different stages emerge • New stage == the developing organism + changing E • Mother’s nutrition has effect • Birth: endpoint of conception • Trace E factors to support or threaten development
  3. 3. Prenatal Development Periods Nucleus Cell matter Zona pellucida (1) The germinal period from conception to attachment to the wall of uterus about 8-10 days (2) The embryonic period from attachment to 8th week all major organs form primitive shapes (3) The fetal period bone hardening from 9th week until birth 25% pregnancies end before awareness
  4. 4. The Germinal Period
  5. 5. The First Cells of Life • Cleavage: 24 hours after conception during zygote travelling down the fallopian tube • Hundreds of cells produced by reaching the uterus • Heterochrony (variability in time): different parts of organism develop at different rates • Heterogeneity: variability in levels of development of parts e.g., hearing > seeing
  6. 6. Emergence of New Forms • After 4 or 5 days conception morula cells become smaller as body cell • Morula enters uterus (fluid passes into morula) • Central cells (inner cell mass, later embryo) + outer layer (trophoblast, [1]protective barrier, [2]later membranes for transmitting nutrients, [3]pump life-giving fluid from uterus) [4]remove waste products for dividing cells & growing of organism
  7. 7. Epigenesis What makes the different groups of cells take on different forms? Epigenesis • At the time of generation (Greek) • New form = interaction of preceding form + E • Es in blastocyst: (1)inside cells surrounded by other cells (2)one side cell contacts with zona pellucida (3)mother’s fluid exchanges with E in blastocyst • Interactions between cells (with each other) and E conditions create (1)new kinds of cells (2)new form of interaction between organism & E • Implantation: the process by which blastocyst becomes attached to the uterus (branch to uterus’s blood vessels)
  8. 8. • • • • • • Stem Cells Specialized kinds of cells Have unique ability to renew cells Give rise to wide variety of other cells 1 week after conception Inner cell mass of blastocyst Totipotent (totally potent): any stem cell has potential to develop into a fully formed baby • Pluripotent (multiply potent): after stem cells differentiate into 3 germ layers (胚葉)-mesoderm, endoderm, ectoderm • Replacement cell or tissue sources for Parkinson’s, Alzheimer’s, spinal cord injury, stroke, burns, heart disease, diabetes, rheumatoid arthritis • Stem cell research for human health in ethical ways (currently deliberate abortion in blastocyst [totipotent] & fetuses [pluritopotent])
  9. 9. The Embryonic Period
  10. 10. Sources of Nutrition & Protection 6 weeks in • After implantation, embryonic period Human embryo 3 weeks Human embryo 5 weeks
  11. 11. Functions of Protective Environment • Amnion: thin tough transparent membrane holds amniotic fluid surrounding the embryo • Amniotic fluid: provides liquid support for weak muscles & soft bones & medium for moving & changing positions • Chorion: another membrane & part of placenta • Placenta: complex organ made up from mother & the embryo; barrier from direct contact of bloodstreams of mother & embryo; filter to exchange nutrients & oxygen; converts nutrients from mother’s blood for embryos; enables embryos’ waste products being absorbed eventually by mother’s kidney • Umbilical cord: links embryo & placenta
  12. 12. Embryonic Growth • Inner cell mass begins to differentiate into various kinds of cells which turn into organs • First step: two layers separation (1)ectoderm---outer layer: outer surface of skin, nails, part of the teeth, lens of eyes, inner ear, nervous system(brain, spinal cord, nerves) (2)endoderm---inner layer: digestive system, lungs • Second step: one layer formation (3)mesoderm---middle layer: muscles, bones, circulatory system, inner layers of skin • Organism develops in two patterns: cephalocaudal pattern (from head down), proximodistal pattern (from center to periphery) [spinal cord < arm; upper arm < forearm]
  13. 13. Sexual Differentiation • First 6 weeks after conception no genetically gender difference in structure • Gonadal ridges appear in fetuses • From 7th week male gonadal ridges begin to form testes • Several weeks later, female ovaries begin to form • Male gonads (androgens) == gender key • Testosterone suppresses pituitary gland (for hormone secretion to form female menstrual cycle)
  14. 14. The Fetal Period
  15. 15. Fetal Growth • From 8th/9th week until birth • Length increases from 1.5 inches (3.8cm) to 20 inches (50.8cm) • Weight increases from 0.02 pounds (0.009kg) to 7.1 pounds (10.32kg) • Organ complexity • 10th week intestines in position • 12th week clear gender • 16th week erect head, lower limbs well developed & ear migration from neck to sides of head • Mother’s digestive system & • 5th month fetus’ nerve cells as a person heart == sources of noise • Movements == motion stimuli • 7th month lungs breath & eyes respond to lights • Placenta & umbilical cord == pathways affect the child • 8th month folds of the brain are present • 9th month wrinkled brain • Before birth fetus doubles in weight
  16. 16. Sensory Capacities • How the fetus is influenced by uterine E? (1) Sensing motion: vestibular system (balance) in middle ear functions in 5th month & fully mature at birth sense mother’s postural changes sense itself floating inside fluid-filled E (2) Seeing: 26th week fetus respond to lights (heart rate changes, body movement) (3) Hearing: 5th or 6th month 75 db (air passes through mother’s stomach, mother’s heartbeat, mother’s voice) newborns prefer sounds heard in uterus > mother’s natural voice
  17. 17. Fetal Activity • From 8th week embryo becomes active for development • Body movements in fetal period are varied & coordinated • 15th week fetus acts as newborn head-turning, leg flexing (4th month mom can feel it) • 24th week (6th month) to 32th week (8th month) fetal inactivity (high rate of quiet periods) for neural pathway development • Movement inhibition is related to brain maturation of higher functions
  18. 18. Brain Maturation • Spontaneous fetal activity == crucial in development chick embryo’s prenatal activity correlated with normal limb development • Fetal movements == establish basic neuronal connections in humans • Breathing movements with chest & lungs = respiration muscles
  19. 19. Learning in the Womb • The cat in the hat story • Twice a day for 1.5 month before due • 16 pregnant mothers • 3.5 hours totally • Tested newborns after 2 or 3 days • Half increased sucking rate/half decreased • Newborns’ learning in the womb influenced sounds they found rewarding after birth
  20. 20. Maternal Conditions & Prenatal Development
  21. 21. Maternal Attitudes & Stress attitudes & • Pregnant women’s feelings of the fetus influence children after birth • Unwanted children weighted less & needed more medical help • Under stress or emotionally upset released more hormones (adrenaline & cortisol) via placenta to have effect on child’s motor activity (more aggressive) • Stress relates premature delivery
  22. 22. Nutritional Influences • Folic acid (one member of vitamin B complex) in green vegetables & fruit • Calcium in milk • Iron to prevent birth defects • 1941 Leningrad (St. Petersburg) encircled by German army & resulted in famine until 1942 February • Four slices for factory workers & two slices for everyone else • Infants born were lower than normal & weighted less (< 2500 grams) & premature & poor condition at birth • Nutrition deprivation in early 3 months: CNS defects, premature, death; later 3 months: retard fetal growth
  23. 23. United Nations Children’s Fund (1999), poor economic conditions create a set of risk factors, including poor health conditions, parents’ lack of education
  24. 24. Birth: The First BioSocial-Behavioural Shift
  25. 25. The Baby’s Experience of Birth • • • • Stressful for babies Through narrow opening canal with lots of pressure on head Umbilical cord may be constricted reducing oxygen supply Newborn’s biological mechanisms in birth--surge of adrenaline and other ‘stress’ hormones in the fetus (1) prepare newborns to survive outside the womb (Lagercrantz & Slotkin, 1986) cesarean-section-newborns usually have breathing difficulties facilitate liquid absorption from lungs production of surfactin allow lungs’ functioning well (2) make an increase in newborns’ metabolic rate = nourish cells (3) Increase blood flow to vital organs (heart, brain, lung) (4) put newborns in alert states for about 40 min
  26. 26. Childbirth in the US • Centers for Disease Control and Prevention (2000) • Strong preference giving birth in hospitals (99%) (1) Trained staff providing antiseptic surroundings & help to any complications (2) Professional usage of drugs reducing pain in childbirth • 1915---100/1000 infant death in 1st year, 8/1000 mother death • 1997---7.2/1000; 7.7/100,000 • Two main issues concerned--(1) What is the safest method for dealing with pain during childbirth? (2) What precautions are necessary to ensure the health of the mother and the baby? • Jones (1997)--anesthetics/analgesics/sedatives • Less attentive, more irritable, poorer muscle tone, less vigorous sucking responses, weaker
  27. 27. First Construction of Social Relationship Before birth • Amniotic fluid--providing warm/wet environment • Fetus---receiving oxygen & nourishment through the umbilical cord After birth • Lung---taking in oxygen & exhale carbon dioxide • First breath---shutting off bypass that shunts blood away from lungs to the placenta; close down the umbilical arteries; cut off fetal circulation to the placenta • Sucking---nourishment = Birth is the first bio-social-behavioral shift in human development
  28. 28. Cultural Variations in Childbirth • Bajura, eastern Nepal---women deliver in animal sheds, cut & tie umbilical cord/wash clothes, care for newborns themselves (CARE, 2003) == rural France 19th (Gelis, 1991) • Ngoni, east Africa---make secret to husband, men excluded completely/banished/stuff-removed/return after childbirth (Read, 1968) • Maya, Yucatan peninsula---husband stays, witness the process (Jordan, 1993) • 1/3 home births in Holland (Jordan, 1993)
  29. 29. The Newborn’s Condition • Disappointment of the first image of real neonate’s appearance • Large proportion of baby’s head • Small limbs • Misshapen head after tight squeeze • Skin covered with vernix caseosa (white, chessy substance to protect against bacterial infections), spotted with blood • 5.5-10 pounds normal birth weight • 7-7.5 pounds average in the US • 7% weight loss in the first days for fluid loss • Gain weight 10 after days old • 20 inches normal length
  30. 30. Assessing the Baby’s Viability • Physical condition check---Apgar Scale (1953) • Total score less in 4 = immediate medical attention needed • Behavioural condition check---Brazelton Neonatal Assessment Scale (1984) • Assess developmental process of infants & evaluate intervention effectiveness 1. Orientation to animate objects-visual & auditory (does the baby focus on the examiner?) 2. Pull-to-sit (how well is the baby able to do so?) 3. Cuddliness (how does the baby respond? Passively or cuddle up to the examiner?) 4. Defensive movements (how does the baby react to the cloth on face?) 5. Self-quieting activity (how does the baby quiet herself?)
  31. 31. Parent-Child Relationship • Two factors come into play right after birth--(1) initial reactions to baby’s appearance from parents (2) parents’ expectations for babies
  32. 32. Baby’s Appearance William Fullard & Ann Reiling (1976)---picture Konrad Lorenz (1943) Babyness preference study 1. Adult women: infant pictures 2. 7-12y kids: adult pictures 3. 12-14y teens girls: infant pictures Physiological 4. 14-16y teens boys: infant pictures changes for reproducing Weiss (1977)---malformed offspring 1. Killed by mothers 2. less frequent interaction 3. less loved 4. Less competence attributed from mothers Langlois (1995)--Less-attractive-babygirl-mothers > attractive babygirl-mothers paid attention on others
  33. 33. Social Expectations • Adjustment of expected-gender • Sweeney & Bradbard, 1988--• Female fetuses: softer, littler, cuddlier, calmer, weaker, more delicate, more beautiful than male fetuses • Rubin et al., 1974--• Girls: little, beautiful, pretty, cute, resembling as mothers • Boys: big, resembling as fathers no difference on Apgar Scale of girls and boys Fathers > mothers have stereo-type concept to genders
  34. 34. Does Gender Matter? • • • • What babies are named How they are dressed How they are treated What will be expected in later life • MacFarlane, 1977--• Expectations shape how parents treat babies right from the start • Babies are biological organisms and cultural entities • Babies are shaped by community ideas & have different experiences to adulthood • Men & women have different roles to play
  35. 35. Cultural Organization Zincantecos, south-central Mexico Sons: digging stick, ax, strip of palm for weaving mats Daughters: weaving stick Thus--Genetic force (nature) and environment/culture experience (nurture) shape developments of children The relationship between child and parents that begin at birth is an essential foundation on which later development builds
  36. 36. Mother-Newborn Bonding Mother-infant bonding at birth = important to later development Klopfer et al., 1964--#1 baby goat removed right after birth return later = mother goat attacks it! #2 baby goats stay with mom 5 min being removed several hours return later = mother goat welcome it back!
  37. 37. Maternal Bonding Klaus, Kennell, et al., 1970--Mothers with premature babies were less contacted with /interested in babies after separation in incubators! 1974--Control group: a glimpse after birth, brief contact with newborns between 6-12hr later, 20-30min visit for bottle-feedings every 4hr; baby stays in nursery Experimental group: hold newborns 1hr in 3hr after delivery, skin touch with newborns having diapers, 5hr together every afternoon 3 days = 1-month-later, mothers in EG show more interested in infants, gaze them more, fondle them more than mothers in CG = 11-month-later, EG mothers are more attentive to infants, more responsive to their cries than CG mothers Mother-newborn bonding after birth in close physical contact immediately, they bond together via complex interactions
  38. 38. Premature Caring • Reconsidering Klaus & Kennell’s study 1. Small population (N=14/group), nonrepresentative sampling (poor African Americans) 2. EG mothers might be aware of special treatments influencing their behaviours 3. Replication failures (Eyer, 1992; Rutter, 1995) • • • • Kirsten et al., 2001--Early bonding of parent-infant helps high-risk newborns with premature delivery Furman & Kennell, 2000--Skin-to-skin contact results in increased nutritional benefits & greater parental caring & attention
  39. 39. Prematurity • < 37w gestation age = preterm/premature • Immaturity of lungs (1st) • Digestive/immune system (2nd/3rd): sucking, breathing, swallowing • Preterm-related disorders (4th) • Twins might be born 3w earlier • Young women with immature reproduction system, smoked-moms, poor-health-moms, infected-uterusmoms, having had many pregnancies close together • Poor women are twice higher in rate • Cultural factors (fertility drug & fasting) • Many other unknown reasons
  40. 40. Kangaroo Caring Heart rate & respiration change in incubators & with mothers T1 T2 T3
  41. 41. Low Birth Weight Fetal growth retardation: 10% behind normal grown rate Meara (2001)-->> multiple birth, intrauterine infections, chromosomal abnormalities, maternal smoking, use of narcotics, maternal malnutrition, abnormalities of placenta/umbilical cord Prematurity & low birth weight co-occur always 2/3 newborn death Holcroft, Blakemore, Allen, & Grahem (2001)--= Neurologically-based developmental handicaps The smaller the baby, the greater the risk Holsti, Grunau & Whitfield (2002)--= coordination problem, intellectual capacities decrease 7-11yr vs. normal birth weight = overall poorly on motorcoordinating-tests, intelligence, arithmetic
  42. 42. Developmental Consequences Lorenz (2001)--Normal-size-preterm-babies in gestational age stand a good chance of catching up with full-term babies Foreman et al. (1997)--Still, babies with (1) attention-maintaining problems (2) visual-motor coordination problems in school age Developmental difficulties >> premature babies, low birth weight babies, complex medication history babies Liaw, Meisels & Brooks-Gunn (1995)--Comfortable socioeconomic circumstances & better education mother have benefits in raising children without these factors Strathearn, Gray, O’Callaghan & Wood (2001)--More serious developmental problems in later years if premature babies raised in impoverished environments or having neglectful parents
  43. 43. Environmental Sources of Birth Defeats
  44. 44. Teaching Implications 許靜芬。2012。 環境是健康人格的 基礎。蒙特梭利雙 月刊,103期,第 10-12頁。
  45. 45. Questions?