FOUNDATIONS OF NURSING 722.553
DEVELOPMENT THROUGH THE LIFESPAN: CONCEPTION TO BIRTH
LEARNING OUTCOMES
3. DISCUSS THEORIES OF HUMAN DEVELOPMENT AND BEHAVIOR
SESSION LEARNING OUTCOMES
• UNDERSTAND THE PROCESS OF DEVELOPMENT FROM CONCEPTION TO BIRTH
• IDENTIFY THE RISK FACTORS ASSOCIATED WITH PREMATURITY
• IDENTIFY MATERNAL RISK FACTORS; BOTH INTERNAL AND EXTERNAL
• IDENTIFY THE COMMON ANTENATAL TESTING PERFORMED IN NEW ZEALAND AND THE
REASONS THEY ARE USED
WE WILL EXAMINE THE BIOLOGICAL PROCESS OF
HUMAN DEVELOPMENT
TRUE OR FALSE…
The study of development
begins at birth.
TRUE OR FALSE…
THE STUDY OF DEVELOPMENT BEGINS
AT BIRTH.
FALSE
THE STUDY OF DEVELOPMENT BEGINS AT THE MOMENT OF CONCEPTION
EVERY HUMAN BEGINS VERY
SIMPLY WITH THE MEETING
OF ONE SPERM AND ONE
OVUM (EGG).
IT’S ACTUALLY PRETTY
UNLIKELY!
THE SPERM
COMPETE TO BE
THE ONLY ONE
THAT CAN
SUCCESSFULLY
FERTILIZE THE EGG.
THE FIRST FORM OF LIFE
• AT CONCEPTION THE
GENETIC MATERIAL
FROM EACH PARENT IS
FUSED.
• A LIVING CELL CALLED
THE ZYGOTE IS FORMED
WITHIN HOURS.
DNA!
• ARRANGED INTO
CHROMOSOMES
• 23 PAIRS IN HUMANS
• 20,000 GENES IN THE HUMAN
GENOME!
• WHAT IS A GENE?
https://d2gne97vdumgn3.cloudfront.net/api/file/8wChD3WNR2SNqtEbQ38u
GENETICS TERMS
• GENOTYPE IS:
• PHENOTYPE IS:
• SINGLE NUCLEOTIDE POLYMORPHISM IS:
• INDEPENDENT ASSORTMENT IS:
DOMINANT AND RECESSIVE
GENES
• DOMINANT GENES—WILL ALWAYS BE
EXPRESSED IF PRESENT
• RECESSIVE GENES—WILL NOT BE
EXPRESSED UNLESS THEY ARE IN A PAIR
• CO-DOMINANT: EXPRESSED EQUALLY EG:
BLOOD TYPE
• IF DOMINANT AND RECESSIVE GENES LINK,
DOMINANT WILL WIN
http://joledingham.ca/double-recessive/?hilite=%27double%27%2C%27reccessive%27
SEX LINKED TRAITS
• TRAITS LINKED TO THE X OR Y (SEX)
CHROMOSOMES
• USUALLY RECESSIVE AND CARRIED
ON THE X CHROMOSOME
• APPEAR MORE FREQUENTLY IN ONE
SEX THAN ANOTHER
• COLOR BLINDNESS, BALDNESS,
HEMOPHILIA, FRAGILE X
TRUE OR FALSE?
50% OF FERTILIZED EGGS ARE LOST BEFORE A
WOMAN FINDS OUT SHE'S PREGNANT.
TRUE OR FALSE?
50% OF FERTILIZED
EGGS ARE LOST
BEFORE A WOMAN
FINDS OUT SHE'S
PREGNANT.
TRUE!
FROM ZYGOTE TO HUMAN??
• THE ZYGOTE WILL BECOME TRANSFORMED THROUGH A
PROCESS OF THREE STAGES:
• GERMINAL PERIOD– THE FIRST TWO WEEKS, FROM
FERTILIZATION TO IMPLANTATION
• EMBRYONIC PERIOD- THE 3RD TO THE 8TH WEEK AFTER
CONCEPTION. MAJOR ORGANS AND ANATOMICAL
STRUCTURES BEGIN TO FORM. HEART (NO LARGER THAN A
POPPY SEED) CAN BE SEEN BEATING AT 6 WEEKS VIA
ULTRASOUND.
• FETAL PERIOD- THE NINTH WEEK AFTER CONCEPTION TO
BIRTH. ALL MAJOR ORGANS CONTINUE RAPID GROWTH AND
BECOME INTERCONNECTED
EVENTS IMMEDIATELY FOLLOWING SPERM PENETRATION
CLEAVAGE FROM ZYGOTE TO BLASTOCYST
Blastulation:
Formation of a hollow
ball of cells filled with
fluid
CLEAVAGE
GASTRULATION – INNER CELL MASS
(EPIBLAST) FORMS 3 GERM LAYERS THAT WILL
BECOME ALL YOUR TISSUES
EVENTS OF PLACENTATION, EARLY EMBRYONIC DEVELOPMENT,
AND EXTRAEMBRYONIC MEMBRANE FORMATION
Amniotic cavity
Endometrium
Lacuna (intervillus
space) containing
maternal blood
Primary
germ layers:
• Ectoderm
Chorionic villus
Maternal
blood vessels
• Mesoderm
Chorion
Proliferating
syncytiotrophoblast
• Endoderm
Amnion
Forming
body stalk
Cytotrophoblast
Amniotic cavity
Yolk sac
Bilayered
embryonic
disc:
Allantois
Extraembryonic
mesoderm
• Epiblast
• Hypoblast
Chorion
being formed
Endometrial
epithelium
Extraembryonic
coelom
Lumen of uterus
(a) 71/2-day implanting
blastocyst
(b) 12-day implanted
blastocyst
(c) 16-day embryo
EMBRYONIC DEVELOPMENT: TISSUES
HELLO EMBRYO!
DURING THE EMBRYONIC STAGE,
IT IS STILL NOT RECOGNIZABLE
AS A HUMAN.
The neural tube
forms (at 22 days),
which becomes
central nervous
system
https://geneticliteracyproject.org/wp-content/uploads/2017/03/embryos.jpg
4 WEEK EMBRYO
FROM 4 TO 6 WEEKS…
LOOK AT THE DIFFERENCE!
TRUE OR FALSE?
• APPROXIMATELY 20% OF ALL EMBRYOS ARE
ABORTED SPONTANEOUSLY
TRUE OR FALSE?
APPROXIMATELY 20% OF ALL EMBRYOS ARE ABORTED
SPONTANEOUSLY
TRUE! THIS IS MOST OFTEN DUE TO CHROMOSOMAL
ABNORMALITIES
6 WEEK-OLD EMBRYO
7 WEEKS…NOW WHAT DO YOU SEE?
7 WEEKS…
NOW WHAT DO YOU SEE?
• LEGS, FEET AND WEBBED TOES
HAVE BEGUN TO DEVELOP
• A BLOOD VESSEL THAT WILL
BECOME HEART BEGINS
PULSATING AROUND THIS TIME.
• THE EMBRYO IS 2 ½ CENTIMETERS
LONG
8 WEEKS
• THE EMBRYO IS NOW
‘RECOGNISABLE AS HUMAN’
• THE EMBRYO NOW WEIGHS 1
GRAM AND IS 1 INCH LONG
• ALL THE BASIC ORGANS AND BODY
PARTS OF A HUMAN BEING
(EXCEPT SEX ORGANS)
• THE “TAIL” IS NO LONGER VISIBLE
AND IS NOW INCORPORATED INTO
THE LOWER SPINE
8 week embryo
THE PLACENTA ALSO FORMS
DURING THIS EARLY PERIOD, AND IS
COMPLETE BY THE END OF THE 1ST
TRIMESTER (12 WEEKS)
•
THE PLACENTA IS A MASS OF TISSUE
ATTACHED TO THE UTERINE WALL
THAT ACTS AS A LIFE-SUPPORT
SYSTEM FOR THE FETUS
•
CONNECTS ITS CIRCULATORY SYSTEM
WITH THE MOTHER
•
THE EMBRYO AND PLACENTA ARE
CONNECTED BY THE UMBILICAL CORD
FUNCTIONS OF THE
PLACENTA
• Diffusion of oxygen
and nutrients
(foetal circulation)
• Secretion of
hormones
THE FETUS: WEEK 9 TO BIRTH
• THE BRAIN
GROWS
DRAMATICALLY
(6 TIMES IN
SIZE) AND
BECOMES
RESPONSIVE
DURING THIS
TIME.
THE BRAIN MUST BE ABLE
TO SUSTAIN THE BODY FOR
SURVIVAL
WITHOUT PROPER BRAIN
DEVELOPMENT, THE MOST
ADVANCED TECHNOLOGY CANNOT
KEEP THE BODY ALIVE
SECOND TRIMESTER
• 13 TO 26 WEEKS GESTATION
• FOETUS ASSUMES MORE DISTINCT HUMAN APPEARANCE
• QUICKENING
• BABY BEGINS TO SWALLOW AND KICK
• NAILS BEGIN TO HARDEN AND THE SKIN THICKENS
• EYE LASHES, BROWS AND SCALP HAIR APPEARS DURING 20 – 24 WEEKS LANUGO STILL
COVERS BODY
• VISUAL AND AUDITORY SENSES BECOME FUNCTIONAL
• BONE CELLS REPLACE CARTILAGE
• OVERALL SIZE INCREASES REMARKABLY
• INTESTINES ARE FUNCTIONAL
SECOND TRIMESTER
• 24 WEEKS FAT BEGINS TO DEVELOP
UNDER THE SKIN
• EYES ARE NO LONGER FUSED THEY ARE
COMPLETE
14-16 WEEKS
TRUE OR FALSE?
RESEARCH SHOWS
THAT FETUSES CAN
DEVELOP SIGHT
VERY EARLY IN THE
WOMB.
RESEARCH
SHOWS THAT
FETUSES CAN
DEVELOP SIGHT
VERY EARLY IN
THE WOMB.
FALSE!
THIRD TRIMESTER
• 28 weeks eyes open and close and respond to light,
fingernails appear
• Better organized gross motor skills, sleep – wake cycles
• Minimal surfactant production
• 32 weeks responds to external sounds
• brain is 25% of adult weight
• 36 weeks lanugo disappears 50% of birth weight
gained, brain development slows and is more convoluted
• 40 weeks myelination of brain begins
• Smooth skin and hair on head (moderate)
• Lanugo only on shoulders
• Body systems prepared for life outside the womb
• Positioned head down
24 weeks (6 months)
32 weeks (8 months)
36-38 WEEKS
FETUSES SPEND ROUGHLY 90% OF
THEIR TIME IN THE WOMB ASLEEP.
FETUSES SPEND ROUGHLY 90% OF
THEIR TIME IN THE WOMB ASLEEP.
TRUE!
Teratogens are drugs, chemicals, or even infections that can cause abnormal fetal development. There are billions of potential
teratogens, but only a few agents are proven to have teratogenic effects.
http://www.columbia.edu/itc/hs/medical/humandev/2005/HD19/TeratogensSyllabus.pdf
http://78.media.tumblr.com/tumblr_m2m4q2GtJF1qcmrkno1_r1_1280.jpg
WHEN DOES A FETUS BECOME VIABLE??
• 23 WEEKS GESTATION IS NOW CONSIDERED VIABLE
• 20 - 35% SURVIVAL AT 23 WEEKS
• 50 – 70 % SURVIVAL AT 24 – 25 WEEKS
• UP TO 90 % SURVIVAL BEYOND 26 WEEKS
BUT..... THIS IS NOT WITHOUT RISK AND A LARGE
PERCENTAGE OF BABIES BORN PRIOR TO 29 WEEKS
FACE SOME FORM OF IMPAIRMENT RELATED TO THEIR
PREMATURE BIRTH!!
HAZARDS OF PREMATURITY
• INCREASED RISKS OF COMPLICATIONS IF BORN
BEFORE 37 WEEKS
• RISKS OF COMPLICATIONS INCREASE WITH
DECREASING GESTATION
• REQUIRE ADMISSION TO NEONATAL INTENSIVE
CARE
• SHORT TERM COMPLICATIONS
• LONG TERM COMPLICATIONS
SHORT TERM COMPLICATIONS
• BREATHING: APNOEA OF PREMATURITY BRONCHO PULMONARY DYSPLASIA
• HEART PROBLEMS: PATENT DUSTUS ARTERIOSUS (PDA) AND HYPOTENSION
• TEMPERATURE INSTABILITY: REDUCED FAT, MINIMAL BROWN FAT STORAGE. THIS LEADS TO BREATHING ISSUES
AS WELL AS HYPOGLYCEMIA
• GASTROINTESTINAL PROBLEMS: NECROTISING ENTERCOLITIS
• BRAIN PROBLEMS: INTRAVENTRICULAR HEMORRHAGE
• BLOOD PROBLEMS: ANAEMIA AND JAUNDICE
• METABOLIC ISSUES: HYPOGLYCEMIA
• IMMUNE SYSTEM DISORDERS: UNDERDEVELOPED IMMUNE SYSTEM
LONG TERM COMPLICATIONS
• CEREBRAL PALSY
• IMPAIRED COGNITIVE SKILLS
• VISION PROBLEMS
• HEARING PROBLEMS
• DENTAL PROBLEMS
• BEHAVIOURAL AND PSYCHOLOGICAL PROBLEMS
• CHRONIC HEALTH ISSUES
• SUDI – SUDDEN UNEXPECTED DEATH IN INFANCY
WHAT FACTORS CAN INFLUENCE PRENATAL
DEVELOPMENT IN THE FETUS, AND THE HEALTH OF
THE MOTHER?
• THINK – PAIR - SHARE
PRENATAL
INFLUENCES
ON DEVELOPMENT
• NUTRITION
• ANXIETY
• MOTHER’S GENERAL HEALTH
• MATERNAL AGE
• TERATOGENS—ANY AGENT
THAT CAUSES
A BIRTH DEFECT (E.G., DRUGS,
RADIATION, VIRUSES)
• DISEASE
• SMOKING
• ALCOHOL AND DRUG USE
Health issues
during pregnancy
•
•
•
•
•
•
•
Anemia
Depression
Ectopic pregnancy
Fetal development issues
Gestational diabetes
Blood pressure
Hyperemesis gravidarum
(extreme morning sickness!)
• Miscarriage
• Placenta previa
• ..and others
Fetal alcohol spectrum disorders: a wide
range of disorders that develop when the
fetus is exposed to alcohol during
development (through the mother’s blood).
Comprised of birth defects, neurological,
behavioural, and growth issues as well as
delayed development.
Phocomelia due to Thalidomide: was used
against nausea and to alleviate morning
sickness in pregnant women.
https://www.health.govt.nz
/your-health/conditionsandtreatments/disabilities/fet
al-alcohol-spectrumdisorder-fasd
SCREENING TESTS
• NUCHAL TRANSLUCENCY SCAN
• PERFORMED 12 -13 WEEK ULTRASOUND, FLUID FILLED SPACE AT THE BACK OF BABY’S NECK
MEASURED
• MATERNAL SERUM SCREENING
• BLOOD ANALYSIS (HCG, ALPHA-FETAPROTEIN AND UNCONJUGATED ESTRIOL (PRODUCED BY
PLACENTA)
• 80 % OF NUERAL TUBE DEFECTS AND TRISOMY 21 IDENTIFIED
SCREENING TESTS
DIAGNOSTIC OR INVASIVE TESTS
THESE MORE COMPREHENSIVE TESTS MAY BE PERFORMED WHEN:
• THE WOMAN IS OVER 35 YEARS OF AGE
• A SCREENING TEST HAS INDICATED THAT THERE MAY BE AN INCREASED RISK
• THE WOMAN HAS HAD A PREVIOUS CHILD OR PREGNANCY WITH SOME KIND OF CHROMOSOMAL
ABNORMALITY
• THERE IS A FAMILY HISTORY OF GENETIC ABNORMALITY.
ANTENATAL HIV SCREENING, ALONG WITH FIVE OTHER BLOOD TESTS, IS OFFERED TO ALL
PREGNANT WOMEN AS A ROUTINE PART OF THEIR ANTENATAL CARE.
INVASIVE TESTING
CHORIONIC VILLUS SAMPLING :
•
CARRIED OUT BETWEEN 10-12 WEEKS GESTATION
•
EITHER BY CATHETER THROUGH THE CERVIX OR A FINE NEEDLE ASPIRATE THROUGH THE ABDOMEN.
•
A SAMPLE OF CHORIONIC VILLUS TISSUE (THE TISSUE THAT WILL EVENTUALLY BECOME PLACENTA) IS TAKEN AND TESTED.
•
COMES WITH A SMALL RISK OF MISCARRIAGE WHICH IS LESS THAN 1 PERCENT.
AMNIOCENTESIS:
•
FOR DETECTING DOWN SYNDROME AND OTHER CHROMOSOMAL ABNORMALITIES, THIS IS CONSIDERED TO BE THE MOST ACCURATE TEST AND
•
IS USUALLY PERFORMED DURING WEEKS 15-16 OF PREGNANCY. UNDER ULTRASOUND GUIDANCE, A FINE NEEDLE IS INSERTED THROUGH THE
ABDOMEN TO WITHDRAW A SMALL AMOUNT OF AMNIOTIC FLUID FOR FURTHER TESTING.
•
ALSO A VERY SMALL RISK OF MISCARRIAGE - LESS THAN 1 PERCENT
INVASIVE TESTING
WHAT ARE NEURAL TUBE DEFECTS?
• NEURAL TUBE DEFECTS ARE SERIOUS ABNORMALITIES WHICH OCCUR IN THE DEVELOPMENT OF THE BRAIN AND SPINAL
CORD IN ABOUT 1 IN 500 BABIES. THE CAUSE IS, AS YET, UNKNOWN. THE TWO MOST COMMON FORMS ARE
ANENCEPHALY AND SPINA BIFIDA.
ANENCEPHALY :
• ABNORMAL DEVELOPMENT OF THE BABY'S BRAIN AND SKULL AND BABIES WITH ANENCEPHALY USUALLY DIE SOON
AFTER BIRTH.
SPINA BIFIDA:
• THE BABY'S SPINE DOES NOT FORM PROPERLY. BABIES WITH SPINA BIFIDA MAY HAVE PARALYSIS OF THE LEGS, LACK
OF BLADDER AND BOWEL CONTROL, AND CURVATURE OF THE SPINE. HYDROCEPHALUS (TOO MUCH FLUID AROUND
THE BRAIN) CAN ALSO OCCUR.
APGAR SCORING
DID YOU KNOW?
• THE FOETUS WILL RESPOND TO NOISE AND CAN HEAR IN THE UTERUS FROM ABOUT 25
WEEKS
• AT 25 WEEKS GESTATION THE EYELIDS OPEN AND CLOSE
• BY 28 WEEKS GESTATION THE TASTE BUDS HAVE DEVELOPED
• NEW RESEARCH (USING ULTRASOUNDS) CAN TEST FETAL REACTIONS TO SOUNDS AND TASTE
• THE FOETUS CAN TELL WHETHER THE AMNIOTIC FLUID TASTES BITTER, SWEET OR SOUR
• AT 33 WEEKS THE BABY BECOMES SENSITIVE TO CHANGES IN LIGHT AND MAY RESPOND BY
KICKING
• BY 34 WEEKS THE PROCESS OF BRAIN FORMATION IS COMPLETE
• THE FOETUS CAN FEEL PAIN
• BABIES ARE BORN WITH THE ABILITY TO DISTINGUISH THE SPEECH SOUNDS WHICH MAKE UP
LANGUAGE AND RECOGNISE THEIR MOTHERS VOICE
• PLAY WITH THE UMBILICAL CORD, THEIR HANDS AND FEET