Chapter 2: Prenatal Development and The Newborn Period Flashcards
Ovulation
First half (day 1-14): estrogen phase (building up endometrial lining)
Second half (day 14-28): progesterone phase (lining becomes soft, spongy, and wet.
Bleeding starts the cycle, ovulation is in the middle (usually day 10-14) and implantation usually occurs around day 22.
Signs of Ovulation
–> Discharge: mucus becomes more substantial, thinner, and slippery, provides good host environment for sperm to survive + reach egg
- if you want to be pregnant then its best to do it before ovulation as the sperm lives longer than the egg
- -> Cervical position change (about to ovulate)
- -> Middlesschmertz (about to ovulate)
- -> Basal temperature rises (after ovulation)
What does the endometrial lining provide?
nutrients to the fertilized egg
Period of Zygote
- Fertilization - 2 weeks
From conception to implantation,
blastocyte from implantation to 7-9 weeks
Period of the Zygote: support structures
–> Trophoblast: Amnion - encloses organism, amniotic fluid
- -> Chorion - becomes lining of placenta
- -> Placenta - semi permeable organ
- -> umbelical cord
Period of the embryo: first month
- rapid growth
- -> early on: 3 cell layers
- ecoderm: nervous system, skin, and hair
- mesoderm: muscles, bones, and circulatory system
- endoderm: becomes digestive system, lungs, urinary tract, other vital organs
- -> Neural tube: FOLIC ACID VERY IMPORTANT
Period of the embryo: Second month
- ears formed
- rudimentary skeleton
- limbs development
- brain develops rapidly
- indifferent (genital ridge) gonad appears
- about 2.5 cm long and 4 grams
Period of the fetus
weeks 9-38 - rapid growth and refinement Third Month: fetus able to kick, twist (not felt by mother) swallow, digest, urinate testosterone secreted by testes of males --> 12th week sex can be determined 7.5 cm long > 28g
Sex determination
If Y absent:
- develop ovaries producing estrogen which enables development of the müllarian duct (uterus, oviducts,uppes vagina)
If Y Present:
- Testes form and secrete 2 hormones
- AMH (or MIS) destroys Müllerian duct
- testoserone - masculinizes the fetus
- allow wolffian duct to develop into vas deferens/ seminal vesicles
Second Trimester
months 4-6
- refined motor actions (thumbsucking)
- heartbeat heard with stethoscope
- eyebrows, eyelashes, and scalp hair appear
- vernix (cheesy white substance - protection )
- Lanugo (fine layer of hair)
Brain development - billion of neurons in place (glial cells continue to develop
Third Trimester
Finishing Phase
- organ systems maturing
- weight gain ( small for gestational age is more of a concern than low birth weight when premature)
Age of Viability
22-28 weeks
- survival outside uterus possible
- better if 28-32 weeks
- neural organization
–> males more likely to be premature bc they are genetically xy rather than xx (females)
- moves to head down position in 9th month (ideal birthing position is head down and back up)
Teratogen
agents such as viruses, drugs, chemicals, radiation etc. that can harm developing fetus
Behavioural Teratogen
Harm to brain and nervous system affecting future functioning, emotional, and or intellect
Environmental Influences: Determining the effect of a teratogen
1) Timing: age of organism at time of exposure
2) Amount: dose and over what duration
3) Hereditary: genetic vulnerability
Multiple negative factors worsen the impact
Sensitive periods
Time when particularly susceptible to damage from teratogens
(recall rapid development during embryonic period)
once fully formed, parts are less susceptible to damage
–> long term outcome: may be affected by postnatal care
Types of teratogens
- -> Drugs:
- thalidomide (60’s), DES
- prescription, non prescription
- illicit drugs
- -> Alcohol (FASD)
- -> Chemicals (Mercury, PCB’s etc)
Maternal Teratogens
- diseases, std’s, toxoplasmosis
- diet: adequate nutrients, folic acid
- emotional health ( stress hormones )
- age both young and old
Medications and Childbirth
Positives:
- lower rates of infant and maternal death
Negatives:
- interventions increased
- more epidurals
- induced labour
- c-sections
- can effect: mom infant and future children
Birth
- begins when fetal hormones trigger uterine contractions
- -> can be seen as traumatic or transition
- Contractions raise level of catecholamines (stress hormone) which prepares the fetus for the journey out
- elective c-section babies don’t experience this catecholamine surge
3 stages of labour
Stage 1: dialation and effacement of cervix
–> during transition from stage 1-2 many often become very nauseous and vomit which means your ready to push
Stage :
- pushing and delivery
- -> once head is out then the rest is usually a little easier
Stage 3: placenta delivery
Newborn assessment
- check skin tone to make sure blood flow is good
- apgar test, given minute 1 and again at 3 or 5
- physical condition at birth out of 10 (want to get 7 or better)
Apgar Test
Appearance Pulse Grimace Activity Respiration
what is another commonly used scale at newborn stage?
NBA (Brezelton’s Neonatal Bhavioural Assessment Scale)
Reflex’s, states, reactions,
- a more subtle test that is good for parental training
Post Birth Issues
attachment does not equal bonding
- emotional bonding (contact in first few hours, quite special)
- helps but is not critical
Fathers experience engrossment (overcome with emotion and love)
Postpartum Depression
- more commonly experience by those who have experienced depression before, but doesnt mean that you will or wont get it
- more common when child is unwanted or there are problems with the father
- can still happen with seemingly no cause as well
Low Birth Weight
- associated with outcome - good or bad
- length of baby indicative of final height more than weight
Pre Term
- -> 3 or more weeks early
- outcome depends on many factrors
- surfactin hasnt been produced yet and so lack of this at time of birth can mean that the baby will have lung problems
- respiratory distress syndrome
- respiratory systems is one of the last to be developed so when they arrive early this is where the most concern could be
SGA (Small for Gestational Age)
- weigh less than expected for age
- at greater risk for major complications
>5 pounds = magic#, much better outcomes
outcomes of preterm babies
- long term consequences are possible
- in part depends on the type of care provided
- hospital care stresses the importance of skin to skin contact and care
- stimulation also important
- “kangaroo care” started from hospitals that lacked resources
- training of hospital or care personnel
Reflexes
Survival:
- breathing
- blinking
- pupillary
- rooting
- sucking
- swallowing
Primitive reflexes:
- swimming
- stepping
- palmar
- moro
both are:
- inborn automatic
- adaptive value
- related to later development
