9. foetal growth and development 2 (workbook) Flashcards
(27 cards)
what is the foetal period?
the stage of intra-uterine life from the end of the 8th week till term
what happens during the foetal period?
systems laid down during the embryonic period grow and mature to fit the individual for birth and post-natal life
what are the most important body systems for determining survival outside the uterus?
nervous system
respiratory system
CVS system
urinary system
if a baby is born smaller than expected, what is it important to distinguish?
whether the foetus is born prematurely (pre-term)
OR
intra-uterine growth retardation (full term BUT small)
how can age of a foetus be estimated?
- duration of pregnancy
- by developmental criteria
- symphysis (fundal height)
how can duration of pregnancy be used to estimate age of a foetus?
- fertilisation age
2. age since mother’s last menstrual period
when may confusion arise when using duration of pregnancy be used to estimate age of a foetus?
- irregular cycles (age since mother’s last menstrual period)
- whether calendar months used (fertilisation age)
how can developmental criteria be determined to estimate age of a foetus?
accurate measurements and predictions can be made in utero by ultrasound
what are the measurements and predictions used to make in utero estimation of the foetus’ age? (developmental criteria)
- crown-rump (CR) length
- foot length
- biparietal diameter of head
- weight after delivery
- appearance after delivery
what is crown-rump length (CR)?
the length of human embryos from the top of the head (crown) to the bottom of the buttocks (rump)
(head to sacral)
what is biparietal diameter of head?
both sides of the parietal bones of the skull
how is the symphysis (fundal height) used to estimate the foetal age?
distance between symphysis pubis to the top of the uterus (fundus)
how can the symphysis (fundus height) be measured?
measured with a tape measure (e.g. 20cm at 20 weeks, 36cm at 36 weeks, then plateau)
aside from using a tape measurer, how else can the symphysis (fundal height) be measured?
the height of the fundus can be assessed in relation to other structures e.g. umbilicus / xiphisternum
where is the uterus palpable?
above the pelvis after gestational week 12
what is suggestive of intrauterine growth restriction / foetal growth restriction? (using fundal height)
a lag of 4cm or more of the fundal height
what are sources of variability when using the fundus height to measure the foetal age?
- number of foetus
- volume of amniotic fluid
- extent of engagement of head
- the lie of the foetus (position)
how many phases of maturation of the lungs are there and what do they influence?
4 phases
influence the viability of premature infants
what does the survival of the infant depend on?
- presence of thin walled air sacs for gas exchange
2. presence of surfactant to lower surface tension and allow air sacs to expand
what are the histological 4 stages of lung development?
- pseudoglandular (8-16 weeks)
- canalicular (16-26 weeks)
- terminal sac (26 week-term)
- alveolar period
what is the pseudoglandular phase (8-16 weeks)?
NOT viable:
- no air sacs
- airways formed only as far as TERMINAL bronchioles
what is the canalicular phase (16-26 weeks)?
may be viable at end
more VASCULAR, some terminal sacs
what is the terminal sac (26 weeks-term)?
viability improves with age
many terminal sacs and some primitive alveoli
surfactant formed from week 20
what is the alveolar period?
late foetal - 8 years
95% of alveoli are formed post-natally
