SPR L2 Prenatal Development Flashcards
Learning Outcomes
- Describe the stages of prenatal development
- List different environmental factors that may adversely impact upon the development of the foetus
- Describe how environmental factors can interact with the stages of prenatal development to influence foetal outcome with reference to case studies
What are the three stages of prenatal development?
- Period of the Zygote - ovulation to implantation
- Embryonic Period - implatation to 8 weeks
- Foetal Period - 8 weeks to birth
Period of the Zygote
- How many succeed to implant?
- How many of the implants fail to develop?
- What are the reasons for this?
- Give an overview of Week 1
- GIve an overview of Week 2
- 1/2
- 1/2
- Genetic abnormalities, and they burrow into a site that is incapable of sustaining them
- Zygote undergoes Mitosis, Blastocyst Implantation
- Blastocyst is fully implanted, embryonic disk forms
Period of the Embryo
- What happens in the first month?
- What happens in the second month?
- Give an overview of the embryo at the end of this period
- Rapid Growth
Neural tube
Heart
Eyes, ears, nose, mouth
Limb buds
- Rudimentary skeleton
Limbs: forearm-upper arm-hands-fingers
Rapid brain development
Indifferent gonad
Face development: http://ow.ly/tsizl
- By end, embryo is approx. an inch long, weighs 7 grams, but all major organs have formed and it is recognisably human.
Period of the Foetus
Foetus begins to move, sense and behave- individuality emerges.
- Outline the 3rd month
- Outline 4-6th month
- Outline 7-9th month
- Nervous/muscular interconnect – perform manoeuvres
Digestive/excretory interconnect – swallow, digest, urinate
testosterone secretion in males– external genitalia form allowing detection of sex of baby by ultrasound
2. Mouth/lips/tongue /larynx movement become increasingly complex allowing foetus to practice sucking, munching, hiccupping, breathing, coughing, snorting.
Kicks strong enough to be felt, heartbeat easily heard with stethoscope at 4 months and without by 5 months.
Nails/skin thickens, eyebrows, eyelashes, scalp hair appear (5 months)
Sweat glands begin functioning (5 months)
Foetus is covered in vernix caseosa and lanugo.
Visual and auditory senses clearly functional at 6 months– evidence from preterm babies
Foetus reaches ‘age of viability’.
- Organ systems mature (pulmonary alveoli –problem for preterm babies).
Systems start showing better organisation and predictability regarding cycles.
Fat deposition for insulation.
Sleep increases in 9th month and movement is restricted by decreasing space.
When is the second scan carried out?
Why?
Second scan to diagnose illness.
This can also facilitate bonding.
When does the foetus reach the ‘age of viability’?
4-6 months
What is termed the ‘finishing phase’?
7-9 months
Name the three stages of Prenatal Development and when they occur
- Zygote (weeks 1-2)
- Embryo (weeks 3-8)
- Foetus (weeks 9-42)
When does the period of the zygote commence and end?
when the egg is fertilised and ends when the blastocyst is firmly embedded in the uterine wall.
What is the period of the embryo characterised by?
characterised by rapid development: all major organs and limbs are formed
What does the period of the foetus begin with?
What does this allow?
growth and integration of nervous/muscular system and the digestive/excretory system
allowing foetus to move reflexively, to swallow and excrete, and the differentiation of the sex organs
Summary
- What happens as the nervous system matures?
- What gives the baby insulation?
- When is the ‘age of viability’ reached?
- What happens in the ‘finishing period’?
- How is most time spent?
- the brain progressively begins to take control of all major functions including control of the heart and of movement. Reflexes can be seen to facilitate this process, kick-starting a process of continuous feedback that refines movement over time.
- The foetus develops lanugo (downy hair) and is covered in vernix caseosa (waxy white substance)
- around 5-6 months - lungs begin to mature and begin to be able to be capable of breathing air. Lungs are last thing to mature and limit our ability to reduce the age of viability.
- (last three months) increase in body fat, movement is restricted due to loss of space and the brain is fine tuning it’s regulation of functions and it’s interconnections
- Most time is spent asleep.
Outline the 3 risk groups to foetal development
- Genetic abnormalities (10-25%)
- Single environmental agents –teratogens (up to 10%)
- Remainder (majority) result of complex gene-environment interactions that could include:
- Teratogens
- Maternal Nutrition
- Maternal Stress
- Labour complications
What is the majority of risks to foetal development made up by?
Remainder (majority) result of complex gene-environment interactions that could include:
–Teratogens
–Maternal Nutrition
–Maternal Stress
–Labour complications
What is a teratogen?
Give examples
May harm the embryo-foetus-newborn - ‘All or None’ effect at the embryonic phase (before organogenesis)
- Drugs – recreational, iatrogenic
- Ionising Radiation (e.g. X-Rays)
- Viral/bacterial/parasitic infections
- Pb, Hg or other chemicals
- Absent nutrients e.g. folic acid
What are the potential results of teratogens?
- Drug Withdrawal (e.g. Cocaine, Heroin)
- Low birth weight and premature delivery (e.g. Smoking)
- Physical Malformations (e.g. Thalidomide)
- Mental Impairment (e.g. Alcohol-FASD)
- Emotional & Behavioural Disturbances (e.g. Maternal Stress)
- Evidence for gender effects- XY more susceptible
- Miscarriage (e.g. Toxoplasmosis)
For general perusal
Foetal Alchohol Syndrome
Name some of the features seen on the face of the newborn
- Small head circumference
- Simply formed - low set ears
- Thin upper lip
- Small chin
- Small eye openings
- Under eye folds
- Flat midface
- Short upturned nose
- Flat elongated philrum (groves above lip)
Foetal Alchohol Syndrome
How does alcohol affect foetal development?
directly and indirectly by compromising the function of placenta
- Dosage effect
- Social drinking enough to cause Foetal Alcohol Effects (FAEs).
- Risk highest with binge drinking
FASD - Foetal Alchohol Spectrum Disorders
- What are the physical symptoms?
- Which brain areas are commonly affected?
- •Microcephaly – small head, heart, limbs, joints, face
- Facial features
- Lower birth weight and lag in development
- Seizures, tremors
- Cerebellum
Corpus Callosum
Basal Ganglia
Hippocampus
And others…..
What are the behavioral defecits associated with FASD?
- Executive Functioning (e.g. Prefrontal Cortex)
- Cognition/Learning
- Social Skills
- Memory (e.g. Hippocampus)
- Language
- Motor Skills (e.g. Cerebellum)
- Impulse Control (e.g. Basal Ganglia)
- Regulation of Emotion (e.g. Limbic System)
Thalidomide
- What was it?
- What did it result in?
- 1960’s Mild tranquiliser, Over-the-counter medication for morning sickness
- Phocomelia- a rare congenital deformity in which the hands or feet are attached close to the trunk, the limbs being grossly underdeveloped or absent.
Arms (25th-27th day)
Legs (28th-36th day)
Eyes
Ears (taken on 21st day)
Nose
Heart defects
40th day on – no effects
Majority of pregnant women taking drug did not show ill effects.
Pregnancy and Emotional Well-Being
- What can maternal stress cause?
- What is used to assess the health of newborn children?
- may increase risk of preterm birth and result in lower birth weight in children born full-term.
- Apgar - (Appearance, Pulse, Grimace, Activity, Respiration) summarily assesses the health of newborn children.
Pregnancy and Nutrition
- What did the evidence from WW1 suggest?
- What supplements reduce the risk of neural tube abdnormalities?
- What in high doses is a teratogen?
- Malnutrition in first trimester can result in spinal cord defects and miscarriage.
Malnutrition in third trimester can result in babies with low birth weight (see later slides).
- Folic Acid Supplements reduce risk of neural tube abnormalities e.g. spina bifida and reduces risk of Down syndrome.
- Vitamin A
What is the significance of
Low Birth Weight (below 2.5kg)?
Graphs show that infants born with a low birth weight often lag behind with regards to cognitive and language development.
- If infant is premature, it may indicate child is at an earlier stage of development.
- If infant is ‘small for date’, it may indicate serious problem for future development
Both are vulnerable.
Low Birth Weight
Differences can be seen at later stage suggesting that impairment may be long-lasting, particularly in ‘small for date’.
Summary (for general perusal)
- Foetal development can be affected by
- genetic factors
- environmental factors
- complex gene-environment interactions.
- Most ‘environmental factors’ are referred to as ‘teratogens’ – diseases, x-rays, chemicals, absent nutritional factors.
- Additional ‘environmental factors’ include maternal stress and labour complications.
- How these impact foetal development is critically dependent on the stage of development when the ‘environmental factor’ was encountered.
- Low birth weight is often predictive of future vulnerability and cognitive impairments, particularly in infants born ‘small for date’.
Reading
Adler, B., Porter, M. Abraham, C. & van Teijlingen, E. (Eds.) (2009) Psychology and Sociology Applied to Medicine 3rd Edition. London: Elsevier
https://encore.qub.ac.uk/iii/encore_qub/record/C__Rb1846324
Chapter title: Pregnancy and Childbirth:
- Describe how a pregnant woman is viewed and treated in (i) the biomedical model and (ii) the psychosocial model.
- Traditionally, how have pregnant women been viewed in the UK? What evidence exists to challenge this approach?
- What does pregnancy mean for (i) a midwife, (ii) an obstetrician, (iii) a pregnant woman (iv) a pregnant woman’s partner/husband?
Chapter title: Reproductive Issues:
- How do the different facets of reproduction: (i) menstruation, (ii) pregnancy, (iii) childbirth, (iv) menopause, affect women’s lives from a biopsychosocial perspective?
- Contrast the approaches to Postnatal Depression using the biomedical model and the psychosocial model. Which would you consider most effective?
