Prenatal Development & Birth Ching-fen Hsu

2013/10/4

Lecture 3

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

Prenatal Development Periods (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

Nucleus

Cell matter

Zona pellucida

The Germinal Period

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

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

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)

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])

The Embryonic Period

Sources of Nutrition & Protection

• After implantation, 6 weeks in

embryonic period

Human embryo 3 weeks

Human embryo 5 weeks

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

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]

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)

The Fetal Period

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

• 5th month fetus’ nerve cells as a person

• 7th month lungs breath & eyes respond

to lights

• 8th month folds of the brain are present

• 9th month wrinkled brain

• Before birth fetus doubles in weight

• Mother’s digestive system &

heart == sources of noise

• Movements == motion stimuli

• Placenta & umbilical cord ==

pathways affect the child

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

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

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

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

Maternal Conditions & Prenatal Development

Maternal Attitudes & Stress • Pregnant women’s attitudes &

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

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

United Nations Children’s Fund (1999), poor economic conditions create a set

of risk factors, including poor health conditions, parents’ lack of education

Birth: The First Bio-Social-Behavioural Shift

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

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

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

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)

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

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?)

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

Baby’s Appearance William Fullard & Ann Reiling (1976)---picture

preference study

1. Adult women: infant pictures

2. 7-12y kids: adult pictures

3. 12-14y teens girls: infant pictures

4. 14-16y teens boys: infant pictures

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

Konrad Lorenz (1943) Babyness

Physiological

changes for

reproducing

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

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

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

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!

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

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

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-uterus-

moms, having had many pregnancies

close together

• Poor women are twice higher in rate

• Cultural factors (fertility drug & fasting)

• Many other unknown reasons

Kangaroo Caring Heart rate & respiration change in incubators &

with mothers

T1 T2 T3

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 motor-

coordinating-tests, intelligence, arithmetic

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

Environmental Sources of Birth Defeats

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。

Questions?