9. Fetal physiology & development

Question 1

at each ‘stage’ of pregnancy, what type of growth restriction would occur?

Answer 1

1- symmetric
2-mixed
3- asymmetric

Question 2

most significant thing to grow in embryonic period

Answer 2

placenta

Question 3

normal SFH from 20 weeks onwards

Answer 3

directly propertional to week fo gestation +/- 2cm

Question 4

use of 12 week scan

Answer 4

dating scan to determine accurate gestational age, detect multiple pregnancy

can do nuchal translucency scan for abnormalities

Question 5

intrauterine growth restriction can be symmetrical. features of this?

Answer 5

head + abdo circumference proportionally reduced

bipariteal diameter reduced proportionally

fatal length reduced proprtionally

Question 6

intrauterine growth restriction can be asymmetrical. features of this?

Answer 6

abdo circumference reduced

head circumference, bipariteal diameter, femur length normal

Question 7

cause of asymmetrical intrauterine growth deficiency

Answer 7

placental insufficiency e.g pre ecalmpsie

Question 8

cause of symmetrical intrauterine growth deficiency

Answer 8

genetic disorders, TORCH infections

Question 9

viability at 24 weeks, why?

Answer 9

50/50, some gas exchange possible

Question 10

viability at 28 and 32 weeks

Answer 10

> 70%
90%

Question 11

are lungs mature at birth?

Answer 11

no

Question 12

appearance of immature lungs on xray

Answer 12

light lung

Question 13

first fetal heart beat

Answer 13

5-6 weeks

Question 14

infant mobility increasing during 1st year shows what?

Answer 14

corticospin al tract myelination is incomplete at birth

Question 15

nervous system defects in newborn

Answer 15

spina bifida
cerebral palsy

Question 16

factors that help oxygen movement from maternal to fetal RBCs

Answer 16

-lower oxygen conc in fetal blood
-higher affinity for oxygen
-double bohr effect

Question 17

what does the foramen oval bypass?

Answer 17

RV and lungs

Question 18

what does ductus arterioles bypass?

Answer 18

lungs

Question 19

approx saturation of fetal blood reaching LA

Answer 19

60%

Question 20

factors to help close shunts at birth

Answer 20

first breath = higher pressure
decreased prostaglandins
umbilical vein closes off, so venosus shuts

Question 21

why can amniotic fluid test for genetic conditions?

Answer 21

contains fetal DNAme

Question 22

meconium staining is a sign of what?

Answer 22

fetal distress (amniotic fluid stained by meconium)

Question 23

use of amniocentesis

Answer 23

karyotyping for genetic conditions e.g. down’s, Edwards, Patau’s

Question 24

risk of amniocentesis

Answer 24

miscarriage 1%