CHAPTER THREE: Prenatal Development, Birth, and the Newborn Flashcards
what are the 3 stages of prenatal development
Takes an average of 38 weeks
Three stages:
1. The period of Zygote (weeks 1-2)
2. The period of Embryo (3-8 weeks)
3. The period of Fetus (9-38 weeks)
- Period of germinal/zygote
- From conception until zygote enters uterus and becomes implanted (8 to 10 days after conception)
- zygote grows rapidly through cell divisions and travels along the fallopian tube toward the uterus
- placenta forms
- this is when twins do or dont develop
- the blastocyst buries deep into the uterine lining. The outer layer forms a membrane (known as an amnion) which encloses the developing organism in amniotic fluid
umbilical cord
- contains a vein that delivers blood loaded with nutrients from the placenta to the zygote, and two arteries that remove waste products
- cord is form, floats freely like an astronaut on a spacewalk
blastocyst
After about four days, the zygote comprises about 100 cells, resembling a hollow ball
- outer layer forms a membrane (amnion)
- protect and nourish developing fetus
placenta
a structure for exchanging
nutrients and wastes between the mother and the developing organism
embryonic period (weeks 3-8)
- most rapid prenatal changes take place
- Once the blastocyst is completely embedded in the uterine wall, it is called an embryo
- organs develop
- sexual differentiation has begun
- teratogens are very harmful
- nervous system develops
- During the second month, limbs start to emerge, and the eyes, ears, nose, jaw, and neck form
what 3 layers form in the embryo
- The outer layer, ectoderm, will become hair, the outer layer of skin, and the nervous
system - The middle layer, or mesoderm, will form muscles, bones, and the circulatory system
- The inner layer, or endoderm, will form the digestive system and the lungs
what does the embryo rest in
The embryo rests in an amniotic sac which is filled with amniotic fluid that cushion the embryo
and maintains a constant temperature
what 2 structures is the embryo linked to
- The umbilical cord houses blood vessels that join the embryo to the placenta.
- The blood flows through the villi –-finger like projections from the umbilical blood
vessels
fetal period (weeks 9-38)
- nervous system, respiratory and digestive systems
- cerebral cortex grow (wrinkled surface of the brain that regulate many important human behaviours)
- males develop testes , females develop ovaries
- eyebrows, eyelashes and scalp hair emerge
- grows in weight and length
vernix
The skin thickens and is covered with a thick, greasy substance called vernix,
which protects the fetus during its long bath in amniotic fluid
age of viability (22-26 weeks)
is the point at which a baby could survive; but born this early, he or she will need assistance to breathe, and has only a slim chance of survival
fetal behaviour
● An active fetus is more likely than an inactive fetus to be an unhappy, difficult baby
The fetuses’ senses work
● They can hear the mother’s beating hear and its mother speak and hear others speak to
her
● Late in pregnancy, enough light passes through the abdominal wall for a fetus to see
teratogens
agents that cause damage to an embryo or fetus
- greatest risk during first 8 weeks of gestation
a) Diseases
b) Drugs
c) Environmental hazards
the 6 general principles apply to all tertatogens:
- The susceptibility of the organism depends on its developmental stage.
- A teratogen’s effects are likely to be specific to a particular organ.
- Individual organisms vary in their susceptibility to teratogens.
- The mother’s physiological state influences susceptibility to teratogens.
- The greater the concentration of a teratogenic agent, the greater the risk.
- Teratogens that have little or no effect on the mother can seriously affect the developing organism
thalidomide
- many women took this drug to help with morning sickness
- were giving birth to
babies witb deformed arms, legs, hands or fingers
teratogenic diseases
- aids
- cytomegalovirus
- genital herpes
- rubella
- syphilis
cigarette smoking and how it affects kid
– the nicotine constricts blood vessels and reduce the oxygen and nutrients
that can reach the fetus through the placenta
- more likely to miscarry
- smaller than average kid
- attention, cognitive and language skills
fetal alcohol spectrum disorder (FASD)
-pregnant women who consume large quantities of alcoholic beverages
- heart problems and atypical facial features
- Leading cause of developmental disabilities in North America
examples of environmental teratogens
- air pollutants
- lead
- mercury
- x rays
- PCBs
spinia bifida
when a mother does not consume adequate amounts of folic acid, a disorder
in which the embryo’s neural tube does not close properly during the first month of
pregnancy (neural tube develops the brain and spinal cord, can cause permanent damage
to nervous stem and spinal cord)
How Teratogens Influence Prenatal Development
- The impact depends on the genotype of the organism
- The impact changes over the course of prenatal development
- Each teratogen affects a specific aspect (or aspects) of prenatal development
- The impact depends on the dose
- Damage is not always evident at birth
how chronic stress affects kid
- weigh less than average
- less able to pay attention
- increasing heart rate and activity level
- weaken immune system
- epigenetic changes
- elevated levels of cortisol
how a mothers age affects kid
- economically disadvantaged
- Older mothers are more likely to have difficulty getting pregnant, miscarriages, and stillbirths (over 40)
- Nearly 50% of pregnancies among women in their 40s and 50s result in miscarriage
- Women in their 20s are twice as fertile as women in their 30s
ultrasound
a procedure using sound waves to generate a picture of the fetus
- can be used as early as 4-5 weeks
- at 20 weeks can reveal sex
- can see date of conception
amniocentesis
a needle is inserted through the mother’s abdomen to obtain a sample of
the amniotic fluid that surrounds the fetus
- typically performed at 16 weeks
chronic villus sampling (CVS)
a sample of tissue is obtained from the chorion (a part of the placenta and analyzed
- Small tube inserted through the vagina into the uterus to collect a small plug of cells from the placenta
- Can be done at 10-12 weeks
non-invasive prenatal testing (NIPT)
- Allows prenatal diagnostic tests for chromosomal abornamilities
- An advantage: might not need to do an invasive procedure like amniocentesis
what are the 3 stages of labour
- dilation of cervix
- delivery of baby
- birth of placenta
stage 1: dilation of cervix
- dilation of the cervix, caused by contractions of the uterus, which become more frequent and more powerful as time goes on
- the longest stage of labor 12 to 14 hours for a woman’s first birth
- force amniotic fluid up against cervix
- At the end, cervix is dilated about 10 cm in diameter
stage 2: delivery of the baby
- begins when cervix is fully enlarged
- use abdominal muscles to push baby
- usually lasts an hour
- crowning (the top of the babys head appears)
- breech presentation (feet first)
stage 3: birth of placenta
- the placenta separates from the wall of the uterus, and is “delivered” in 10 to 15 minutes
claims about eating placenta
- known as placentophagy albeit usually in capsule form
- no clinical evidence to support these claims
- can have negative effects on milk production
epidural
injected into a space below the spinal cord and only the lower body is
nubed = she cannot use her abdominal muscles to help push the baby through the
birth canal
- can cause women to get headaches and decrease blood pressure
- tense = harder birth
doula
is a person familiar with childbirth who is not part of the medical staff
but instead provides emotional and physical support throughout labour and delivery
Bajura Nepal
it’s believed that blood and body fluids associated with birth are pollutants. Childbirth is viewed as being shameful; so shameful, in fact, that nobody assists the mother – she even has to cut and tie her own umbilical cord
Pokot People of Kenya
community celebration - assisted by female relatives, delivers the baby; the father is present to support the mother. Following birth, a burial ceremony is held for the placenta. Mothers are then secluded, given three months free of other chores
postpartum depression
irritability of newborn baby continues for months and is often accompanied by feelings of low self-worth, disturbed sleep, poor appetite and apathy
- changes in hormones
- one way to reduce is breastfeeding
common birth complications
- cephalopelvic disproportion
- irregular position
- pre eclampsia
- prolapsed umbilical cord
hypoxia
If the flow of blood is disrupted, infants do not receive adequate oxygen
- sometimes umbilical cord is pinching or squeed shut
- to guard against this: fetal heart rate should be monitored
premature infants and small for date
are born less than 37 weeks after conception
small for date: infants are substantially smaller than would be expected based on length of time since conception
- premature
kangaroo care
position, in which infants dressed online in a diaper are held against an
adult’s bare chest in a sling or blanket has been popularized in Canadian neonatal units
- skin to skin contact and positive stimulation
natural childbirth
- upright position, rather than flat on her back with her feet in stirrups. This tends to makes labour shorter, as pushing is easier, and more effective with gravity helping out
- the baby also benefits in the mother’s upright position from a richer supply of oxygen as blood flow to the placenta is increased
Apgar Scale
is a measure devised by obstetrical anesthesiologist Apgar, to evaluate a
newborn baby’s condition
5 vital signs are looked for:
1. Breathing
2. Heartbeat
3. Muscle tone
4. Presence of reflexes (e.g., coughing)
5. skin tone
5 scores are added together,
7+ = baby is in good physical condition
4-6 = newborn still needs special attention and care
3 or less = signals a life-threatening situation requiring emergency medical care
Brazelton Neonatal Assessment Scale
- Assesses subtle behavioural aspects of newborns condition
- The scale includes 28 behavioural items along with 18 items that test reflexes
The babies performance is used to evaluate the functioning of four systems:
1. Autonomic - ability to control body functions such as breathing and temperature
regulation
2. Motor - ability to control body movements and activity level
3. State - ability to maintain a state (e.g., staying alert or staying asleep)
4. Social - ability to interact with people
low birth weight
- Below 5 pounds, 8 ounces (2500 grams)
o At greater risk for complications - Small in stature though childhood
- Learning difficulties
- Behavioural problems at school
Main causes for low birth weight: poor nutrition, heavy drug/alcohol use, multiple births
babinski relfex
a babys toes fan out when the sole of the foot is stroked from heel to toe
blink reflex
a babys eyes close in response to bright light or loud noise
moro reflex
a baby throws its arms out and then inward in response to a loud noise or when its head falls
palmar reflex
a baby grasps an object placed in the palm of its hand
rooting reflex
when a babys cheeck is stroked, it turns its head toward the stroking and opens its mout
sucking reflex
a baby sucks when an object is placed in its mouth
withdrawl reflex
a baby withdraws its foot when the sole is pricked with a pin
what r the 4 newborn states
- Alert inactivity - baby is calm and attentive, with eyes open; the baby appears to be deliberately inspecting the environment
- Walking activity - the baby’s eyes are open, but they seem unfocused; the baby moves arms or legs in bursts of uncoordinated motion
- Crying - the baby cries vigorously, usually accompanying this with agitated but uncoordinated motion
- Sleeping - the baby’s eyes are closed and the baby drifts back and forth from periods of regular breathing and stillness to periods of irregular breathing and gentle arm and leg
motion
newborns cry (3 types)
Newborns spend 2-3 hours each day crying or on the verge of crying
- should respond to a babies cry until 3 months old
A basic cry starts softly then gradually becomes more intense and usually occurs when a baby is hungry or tired
A mad cry is a more intense version of a basic cry
A pain cry begins with a sudden long shriek, followed by a long pause and gasping crying
Non REM vs REM sleep
REM: newborns move their arms and legs, they may grimace, and their eyes move beneath their eyelids, body is more active, heartbeat more rapid
NON REM: a baby’s breathing, heart rate, and brain activity are steady, and they lie quite still
Sudden Unexpected Infant Death
a healthy baby dies suddenly, for no apparent reason
- more often when child is on stomach
- born prematurely
- parents smoke
- in Canada, approximately two babies die each week from Sudden Unexpected Infant Death (SUID)
infants sleep patterns
16-19 hours/day
- awake one hour/sleep 3 hours
- by 1 month: 15 hours/day
- by 4 months: 14 hours/day
- most babies sleep through the night at 3 or 4 months
co sleeping
- infants sleep in the cradle next to the bed
Until preschool kids sleep in the same room with parents (interdependent)
