Prenatal dev/premature birth

Question 1

What counts as premature?

Answer 1

Before 37 weeks

Question 2

When is the germinal period?

Answer 2

First 14 days

Question 3

What happens during the germinal period?

Answer 3

Zygote divides as it travels down the fallopian tubes and eventually forms a blastocyst - ball of 16-64 cells

Question 4

When is the embryonic period?

Answer 4

Weeks 3-8

Question 5

When does the embryonic period begin?

Answer 5

Begins as the blastocyst implants in the uterine wall

Question 6

When does organogenesis occur?

Answer 6

During the embryonic period (weeks 3-8)

Question 7

What happens during the embryonic period?

Answer 7

Organs form. Layers of cells differentiate - endoderm, mesoderm, ectoderm - to form specific organs

Question 8

What forms from the endoderm?

Answer 8

Digestive system, lungs, UT, other vital organs

Question 9

What forms from the mesoderm?

Answer 9

Mesoderm - skeleton and muscles, circulatory ststenm, kidney, sexual organs
Arm buds and leg (tail of embryo) begin to form
Heart begins to beat 24 days (3+ weeks) into gestation

Question 10

What forms from the ectoderm?

Answer 10

Ectoderm - hair, skin, nervous system

Ectoderm cells flatten out and turn over neural tube

Question 11

What is the neural tube? What forms from it?

Answer 11

Top end - brain, bottom - spinal cord

Incomplete closure results in defects; anencephaly (no brain) if top not closed, spina bifida if bottom not closed

Question 12

When is the end of the embryonic period? What has happened by now?

Answer 12

At around 8 weeks:
All organs needed to survive are formed
Facial structures fused (Abnormal: cleft palate)
Ears formed
Sexual organs developed
60% volume is head as brain development rapid, quicker than rest of body

Question 13

When is the fetal period?

Answer 13

Last 7 months

Question 14

What happens during the fetal period?

Answer 14

A period of rapid growth and refinement of organ systems, most importantly the lungs
Fetus become more responsive; behaviour becomes regular and integrated

Question 15

When do fetuses become viable?

Answer 15

23 to 28 weeks

Question 16

18 weeks?

Answer 16

Sucking thumb, breathing-like movements. Exercising muscles that will allow lungs to work.

Question 17

24 weeks/6 months?

Answer 17

Baby respond to light outside and sounds outside and inside mother (circulatory system; blood rushing, heart beating)
Limit of viability - 50/50 chance of surviving

Question 18

28 weeks/ 7 months?

Answer 18

Third trimester!

Fetus begins putting on weight in the form of fat

Question 19

30 weeks

Answer 19

Lungs start producing surfactant. Keeps alveoli (pockets in lungs) open. Keeps lungs from collapsing when breathing out

Question 20

Trimesters?

Answer 20

1st trimester - 1-12 weeks
2nd trimester - 13-28 weeks
3rd trimester - 28 weeks to birth

Question 21

When is the limit of viability?

Answer 21

24 weeks; 50/50 chance of survival of first year

Question 22

Risk factors for preterm birth?

Answer 22

Indigenous mothers (possibly due to poor prenatal care; leading to gestational diabetes and high BP that are not well monitored)
Young mothers (40 years)
Multiple birth
First time mums

Question 23

What % of births in Australia are preterm?

Answer 23

7% of births

Question 24

What is done for mothers who go into labour too early?

Answer 24

Medication to stop contractions

Steroids - Speed up lung developm ent (surfactant) before 30-32 weeks

Question 25

Chances of surviving their first year

Answer 25

23 - 74% mortality rate (die in NICU)

24 - 44% mortality rate

Question 26

Factors in predicting outcome?

Answer 26

Gestational age - after 24 weeks better
Birth weight - heavier do better
Gender - girls do better (oestrogen an advantage in lung development?)
Multiple or singleton - singleton do better
Steroids - if mum’s labour is stopped and given steroids, baby does better