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Week 2- Prenatal Development and the Newborn
Learning Objectives:
1. Describe the prenatal development from conception to birth
2. Understand the experience of pregnancy across the three trimesters, including an
understanding of the role of social factors in parental wellbeing
3. Explain the internal and external threats to the developing baby
4. Describe the interventions available to address threats to the developing baby
5. Describe the three stages of childbirth, and the pros and cons of different birth
options
LEARNING OBJECTIVE 1:
FIRST TWO WEEKS:GERMINAL STAGE
- this is the time when the cell mass is not completely attached to the wall of the
uterus
- First 36 hours-fertilized ovum (now cell called zygote) makes the first cell division
- cells continue to divide every 12-15hrs as it takes the 3 day trip down the fallopian
tubes
- once it is past the uterine cavity-the cell sheds its outer wall and becomes different
layers (now called blastocyst) and the rapidly dividing cells form a ball of about 100
cells
- implantation comes next (embedding itself in the cell wall-hormones prepare the
uterus to receive the cell mass) at about day 9 the tentacles developed from the
blastocyst burrow in
- from this landing place, blood vessels multiply which then make up the placenta
WEEK 3 TO WEEK 8 : THE EMBRYONIC STAGE
- most fast paced period of development
- all major organs are constructed in this time period;at the end of this stage the
cells look like a human being
- nutrients are pumped to differentiating cells to nourish the fetus (by third week the
circulatory system forms and the heart starts to beat
- at about the same time (start of week 3) the nervous system starts to appear
- day 21-24 an indentation forms along the back of the embryo and closes up to from
the neural tube (which the spinal cord(lower part) and brain(uppermost part of
neural tube) develop from)
- neurons originate from the neural tube during the first months in the womb
- arm buds form at day 26
- day 28 swellings erupt where legs form
- day 37 feet start to develop
- day 41, elbows, wrist curves and start of fingers can be seen
- toes emerge several days later
- Week 8: the embryo is about the length of the thumb but its internal organs are all
in place
Week 2- Prenatal Development and the Newborn
Principles of prenatal development:
-proximodistal sequence: growth occurs from the most interior parts of the body
outwards
-cephalocaudal sequence: growth occurs in a sequence from head to toe
-mass-to- specific sequence: large structures and movements precede increasingly
detailed refinements (head before eyes)
WEEK 9 TO BIRTH: THE FETAL STAGE
- development occurs at a more leisurely pace
- 9-12 eyebrows, fingernails , hair follicles
- takes full seven months to transform the fully formed embryo into a baby
- this long process is needed to allow for the neurons composing the brain to move
into place
- in the middle of the fetal stage (neurons arrange in the staging area and assume
their mature form, the cells lengthen and develop characteristic branches, then
interlink (responsible for every human thought and action)
- brains doubles in size from month 4 to 7
- month 6, the fetus shows signs of consciousness ie. reacts to sound, hearts
beats faster in response to loud noises, if a doctor signs a light inside the
uterus it tries to shield its face (this stage, if the lungs are mature enough
some babies can be born and survive-earliest stage when babies can live is 22
weeks)
-During final month of pregnancy, there are major support structures the baby
requires, the placenta, umbilical cord allowing the flow of nutrients from the
placenta connected where the belly button will be, and the amniotic sac, a fluid filled
chamber where the baby floats-provides protection from harm and infection
Week 8
Fertilization
4 Weeks
Week 12
Week 16