Fetal growth problems

Question 1

How does development compare with growth?

Answer 1

First 12 weeks fetal development occurs -organs are formed

Then the baby needs to get bigger - fetal growth

Question 2

Define the two types of growth problems

Answer 2

Small for gestational age (SGA)

• <5th centile
• normal variant or growth restricted

Intra-uterine growth restriction (IUGR)

• <5th centile
• growth restricted (i.e. failure to achieve growth potential)

Question 3

How does trophoblast invasion differ between a normal pregnancy and IUGR?

Answer 3

Less trophoblast invasion in IUGR

• Longer intact spiral artery

Question 4

State 5 effects of fetal growth restiction

Answer 4

• deicient placental invasion
• reduced placental reserve
• fetal needs exceed supply
• IUGR
• hypoxia
• fetal vascular redistribution
• oligouria
• abnormal CTG
• fetal death

Question 5

How do you diagnose IUGR?

Answer 5

Clinical suspicion - abdomen looks small

Clinical measurement of uterine size: symphysis - fundal height (SFH)

Ultrasound scan

Question 6

What would symmetrical fetal growth restriction look like on a growth chart?

How does this differ to asymmetrical fetal growth restriction? Causes?

Answer 6

Head circumference low as well as abdomincal circumference

Only the abdomen is affected, normal head circumference

• reflects the size of the fetal liver
• Placental insufficiency is a cause. It leads to no excess glycogen being deposited in the liver

Question 7

Early fetal growth restriction presents as ?

What are the causes?

Answer 7

Symmetrical growth restriction : both head and abdominal growth affected

• Chromosomal anomaly (T21)
• Viral infection (Rubella, CMV)
• Severe placental insufficiency
• or normal small baby (look at parents)

Question 8

What are the consequences of hypoxia in the fetus?

Answer 8

• Blood flow (oxygen and nutrients) redirected to areas of greater importance e.g. the brain
• Blood flow redirected away from areas of lesser importance
  e.g. gut , kidneys and lungs
  (compensated as the fetus doesnt eat and placenta deals with the rest)

Question 9

What are the ultrasound findings in IUGR?

Answer 9

• small abdominal circumference (small liver)
• decreased aminotic fluid (produced by kidneys)
• increased blood flow to brain (investigate middle cerebral arteries using doppler)

Question 10

What are the clinical findings in IUGR?

Answer 10

• SFH smaller than expected
• Babys movements lessen to conserve energy
• Fetal heart rate changes as hypoxia develops (seen on CTG)
• Fetal death

Question 11

How do you decide whether to wait or deliver in IUGR?

Answer 11

WAIT

• if low chance of survival
• give steroids
• reduces need for c section

DELIVER

• if older than 32 weeks
• doppler abnormality identified
• decreased movements
• CTG abnormality

Question 12

How and why would you administer corticosteroids to a fetus?

Give two examples

Answer 12

Betamethasone, dexamethasone

Administration to mother will cross placenta and stimulate alveolar cells to produce surfactant gene

• surfactant stops alveoli wall collapse by reduce surface tension
• helps prevent respiratory distress syndrome –> neonatal death in premature babies
• normally produced from 24-34 weeks, lacking in premature

Question 13

How does blood flow to the middle cerebral artery change in fetal growth restriction?

Answer 13

Normally there is a peak in flow during systole and a negative line (corresponding to a drop in flow) during diastole

In IUGR the blood flow is maintained during systole and diastole –> increasing the blood flow