9. foetal growth and development 2 (workbook)

Question 1

what is the foetal period?

Answer 1

the stage of intra-uterine life from the end of the 8th week till term

Question 2

what happens during the foetal period?

Answer 2

systems laid down during the embryonic period grow and mature to fit the individual for birth and post-natal life

Question 3

what are the most important body systems for determining survival outside the uterus?

Answer 3

nervous system
respiratory system
CVS system
urinary system

Question 4

if a baby is born smaller than expected, what is it important to distinguish?

Answer 4

whether the foetus is born prematurely (pre-term)
OR
intra-uterine growth retardation (full term BUT small)

Question 5

how can age of a foetus be estimated?

Answer 5

1. duration of pregnancy
2. by developmental criteria
3. symphysis (fundal height)

Question 6

how can duration of pregnancy be used to estimate age of a foetus?

Answer 6

1. fertilisation age

2. age since mother’s last menstrual period

Question 7

when may confusion arise when using duration of pregnancy be used to estimate age of a foetus?

Answer 7

1. irregular cycles (age since mother’s last menstrual period)
2. whether calendar months used (fertilisation age)

Question 8

how can developmental criteria be determined to estimate age of a foetus?

Answer 8

accurate measurements and predictions can be made in utero by ultrasound

Question 9

what are the measurements and predictions used to make in utero estimation of the foetus’ age? (developmental criteria)

Answer 9

1. crown-rump (CR) length
2. foot length
3. biparietal diameter of head
4. weight after delivery
5. appearance after delivery

Question 10

what is crown-rump length (CR)?

Answer 10

the length of human embryos from the top of the head (crown) to the bottom of the buttocks (rump)
(head to sacral)

Question 11

what is biparietal diameter of head?

Answer 11

both sides of the parietal bones of the skull

Question 12

how is the symphysis (fundal height) used to estimate the foetal age?

Answer 12

distance between symphysis pubis to the top of the uterus (fundus)

Question 13

how can the symphysis (fundus height) be measured?

Answer 13

measured with a tape measure (e.g. 20cm at 20 weeks, 36cm at 36 weeks, then plateau)

Question 14

aside from using a tape measurer, how else can the symphysis (fundal height) be measured?

Answer 14

the height of the fundus can be assessed in relation to other structures e.g. umbilicus / xiphisternum

Question 15

where is the uterus palpable?

Answer 15

above the pelvis after gestational week 12

Question 16

what is suggestive of intrauterine growth restriction / foetal growth restriction? (using fundal height)

Answer 16

a lag of 4cm or more of the fundal height

Question 17

what are sources of variability when using the fundus height to measure the foetal age?

Answer 17

1. number of foetus
2. volume of amniotic fluid
3. extent of engagement of head
4. the lie of the foetus (position)

Question 18

how many phases of maturation of the lungs are there and what do they influence?

Answer 18

4 phases

influence the viability of premature infants

Question 19

what does the survival of the infant depend on?

Answer 19

1. presence of thin walled air sacs for gas exchange

2. presence of surfactant to lower surface tension and allow air sacs to expand

Question 20

what are the histological 4 stages of lung development?

Answer 20

1. pseudoglandular (8-16 weeks)
2. canalicular (16-26 weeks)
3. terminal sac (26 week-term)
4. alveolar period

Question 21

what is the pseudoglandular phase (8-16 weeks)?

Answer 21

NOT viable:

• no air sacs
• airways formed only as far as TERMINAL bronchioles

Question 22

what is the canalicular phase (16-26 weeks)?

Answer 22

may be viable at end

more VASCULAR, some terminal sacs

Question 23

what is the terminal sac (26 weeks-term)?

Answer 23

viability improves with age
many terminal sacs and some primitive alveoli
surfactant formed from week 20

Question 24

what is the alveolar period?

Answer 24

late foetal - 8 years

95% of alveoli are formed post-natally

Question 25

how are the lungs like at birth?

Answer 25

filled with amniotic fluid aspirated by foetal breathing movements from week 12-14 (together with secreted fluid)

Question 26

what happens to the amniotic fluid at birth?

Answer 26

most is expelled during vaginal birth

any remaining is absorbed

Question 27

what happens to pulmonary resistance with the first breath?

Answer 27

pulmonary resistance falls as the alveoli open

blood flow increases in the pulmonary vessels