Unit 3: Prenatal Development and Birth Flashcards
(29 cards)
What are the three prenatal stages of development?
1) Germinal Period (period of Zygote)
2) Embryonic Period
3) Fetal Period
What occurs during the germinal period of development?
First 2 weeks:
- zygote multiplies it’s cells very rapidly eventually becoming a blastocyst with germ disc in the centre
- zygote makes its way to the uterus for implantation, forming a membrane that encloses the organism with amniotic fluid (amnion)
What occurs during the embryonic period of development?
Weeks 3-8: 2.5cm in size
- sexual differentiation occurs, body structure forms, internal organs begin to develop
- stage where organism is most susceptible to teratogens
- embryo begin to move but mom cannot feel it
1) Ecdoderm layer: outer most layer of cells that eventually becomes hair, skin and nervous system
2) Mesoderm layer: middle layer of cells that become muscles, bones and circulatory system
3) Endoderm layer: inner most layer that becomes lungs and digestive system
What occurs during the fetal period of development?
- All organs including the brain increase in complexity
- fetus begins to use more senses
- fetus spends more time awake
- can distinguish outside sound and rhythm of sound
- 22-26 weeks = age of viability
- 17-22 weeks = mom can feel baby
What is a teratogen?
An agent that causes abnormal development
1) Disease
2) Drugs
3) Environmental Hazards
What are the six principles that apply to all teratogens?
1) Susceptibility depends on the developmental stage of the organism
2) Susceptibility depends on the physiological state of the mother
3) Susceptibility depends on the strength and concentration of the teratogen
4) Susceptibility depends on the organism itself
5) Teratogens typically affect one organ or organ system
6) Teratogens that have little to no effect on the mother can greatly affect the organism
What are the most common diseases that can impact a developing organism (teratogen)?
- Genital herpes
- syphillis
- Rubella
- Aids
- Zika virus (caused by infected mosquitoes and results in small head)
What are the most common drugs that can impact a developing organism?
Thalidomide: common drug prescribed in the 1950s to help pregnant women combat morning sickness - adverse effects caused physical abnormalities in children
Alcohol: causes fetal alcohol syndrome *leading cause of developmental disability in North America
Caffeine: Can stunt muscle tone, low birth weight
Nicotine: cognitive impairment and retarded growth
Marijuana: low birth weight, less motor control
Smoking: contracts blood vessels reducing the flow of oxygen to the baby through the placenta
What are the most common environmental hazards that can cause developmental abnormalities? (teratogen)
- contaminated water associated with industrial waste is the most common enviro teratogen
- air pollutants
- lead
- mercury
- PCBs
- X-rays
What are other general risk factors that can impact development?
- Nutrition
- inadequate nurtition can result in low birth weight or premature birth
- Folic Acid is essential to ward off Spina Bifida (cleft spine) which causes permanent damage to the spinal cord and nervous system - Chronic Stress
- Refers to how a person responds physically and psychologically to threats and challenges
- Stress secretes the hormone cortisol which reduces the flow of oxygen to the fetus while also increasing it’s heart rate and activity level which in turn reduces the flow of oxygen to other organs
- stress can weaken a mother’s immune system making her more susceptible to illness - Mother’s Age:
- greater likelihood of miscarriage and stillbirths
- higher risk of down syndrome
- 50% of pregnancies for women in their 40s and 50s end in miscarriage
What are the four types of prenatal diagnosis and treatment?
- Ultrasound: uses sound waves to generate pictures of the fetus
- Amniocentesis: needle is inserted into the stomach of the mother to draw a sample of the amniotic fluid
- Chorionic Villus Sampling: Sample of tissue is obtained from the placenta
- Non-Invasive Prenatal Sampling: uses fragments of fetal DNA found in the mother’s blood
What are the three stages of labour?
1) Dilation of Cervix
2) Birth of baby
3) Birth of the placenta
What occurs during the dilation of the cervix?
- cervix begins to open to make way for baby to make its way through the birth canal by way of contractions
- full dilation is 10cm
- longest stage of labour
- can last 12-14 hours with first baby and 4-6 hours with subsequent births
What occurs during the delivery of the baby?
- cervix is fully dialted (10cm)
- contractions continue to the point where the mother feels the urge to push
- can take approx 1 hour to push the baby through the birth canal
What occurs during the delivery of the placenta?
- Once the baby is delivered, the placenta detaches from the uterine wall and is delivered which can take between 10-15mins
What is Placentophagy?
The practice of eating or consuming the placenta in some form (often in pills) with the idea that the nutrients in the placenta will help the mother to recover more quickly
–> debunked by researchers who have shown that the nutrient concentration is not high enough to produce any substantial health benefits
–> consuming placenta can cause blood clots and hamper milk production
What are the five most common types of birth complications?
- Cepholopelvic Disproportion: when baby’s head is disproportionately large to the mother’s pelivs
- Irregular Position: When buttocks or should comes out first
- Pre-eclampsia: condition that develops during pregnancy characterized by protein in mother’s urine, high blood pressure and fluid retention - can lead to premy birth
- Prolapsed Umbilical Cord: when umbilical cord precedes the baby in exiting the birth canal which can cut oxygen to the baby
- Post Partum Depression: 10-15% of new mom’s have PPD
What is the birth culture of the Banjura people of Nepal?
Belief that blood and body fluid associated with birth are pollutants and therefore birth is seen as shameful. Women birth alone.
What is the birth culture of the Pokot people of Kenya?
Birth is considered a community event where close female relatives assist with the birth, there is a burial ceremony for the placenta and the mother has time off from her chores to rest.
What has been the evolution of birthing culture in Western nations?
- in the 1800s birth took place at home
- during the industrial revolution, more people moved to cities and therefore began birthing in hospitals
- in the 1960s many women began questioning birthing practices used by doctors specifically in regards to the high doses of medication used
- This led to the natural birth movement of the 1970s
- Today, woman have more choice
What are the three most common approaches to birth?
1) Natural Birth: make childbirth rewarding for the mother
2) Home Birth
3) Labour and delivery medication births (often in hospitals - used in 80% of births in North America)
What is the baby’s experience during birth?
Stressful but not traumatizing. Stress allows for:
- lungs to function
- increase in metabolic rate
- induces state of alertness
What is the Apgar Scale ?
- Named after Virginia Apgap
- Screens for risks of physical problems
- Predicts aspects of future development
Looks at:
1) heart rate
2) respiratory effort
3) Muscle tone
4) Reflex responsivity
5) Colour
Perfect Score of 10: heart rate above 100 beats per minute + strong cry + active motions with muscles + cries and pulls away when reflexes are tested + pink in the face
What is the Brazelton Neonatal Assessment Scale?
Tests behaviour aspects of a newborn’s condition. Low score may indicate brain damage, neurological problems or insecure emotional attachment.
Tests:
1) reflexes
2) motor capacity
3) responsiveness to objects and people
