LGA + SGA

Question 1

What is macrosomia?

Answer 1

Weight of newborn is 4.5+ at birth

LGA = is during pregnancy too - estimated foetal weight 90th+ percentile

Question 2

What are the causes of LGA?

Answer 2

• Constitutional
• Maternal GDM
• Previous macrosomia
• Maternal obesity
• Overdue baby
• Male baby

Question 3

How can macrosomia be a risk to mother?

Answer 3

shoulder dystocia
Perineal tearing
need for instrument or CS
PPH
uterine rupture

Question 4

What is shoulder dystocia?

Answer 4

• inability to deliver the body of the fetus using gentle traction after head has already been delivered. Due to impaction of anterior fetal shoulder on maternal pubic symphysis.

Question 5

What can macrosomia to do baby?

think acute + long term effects

Answer 5

Birth injury
Neonatal hypoglycaemia
Childhood obesity and later life T2DM

Question 6

What 3 measurements are used to identify large for age prenatal?

Answer 6

Symphysis - fundal height (SFH)

Abdomnal circumference (AC)

Estimated foetal weight (EFW)

Question 7

After 24 weeks what changes with fundal height measurements?

Answer 7

Only expect it to increase 1cm a week

any quicker can indicate large for dates

Question 8

What may be identified on pregnant lady examination of a LGA baby

Answer 8

Excessive distention for gestational age

Abdomen : increase SFH, Increased abdominal circumference

Question 9

Investigations for macrosomia?

Answer 9

US - to exclude polyhydramnios
US - to estimate fetal weight

OGTT - Gestational diabetes

Question 10

Management plan for LGA?

Answer 10

Reduce risk of shoulder dystocia - offer caesarean section

Question 11

What is SGA?

Answer 11

Fetus that measures <10th centile for their gestational age

Question 12

What two measurements are used to assess fetal size?

Answer 12

Estimated foetal weight + fetal abdominal circumference

Question 13

What is considered low birth weight

Answer 13

<2.5kg

Question 14

Causes of SGA can be divided into which two categories?

Answer 14

** Constitutionally small **(match mother and family, growing appropriately on growth chart)

- Intrauterine growth restriction (reduced growth rate due to pathology of nutrients and oxygen delivered by placenta) :
–> placenta mediated growth restriction
–> non-placenta mediated growth restriction

Question 15

How can IUGR be further classified?

Answer 15

Intrauterine growth restriction (reduced growth rate due to pathology of nutrients and oxygen delivered by placenta) :
–> placenta mediated growth restriction
–> non-placenta mediated growth restriction

Question 16

What can cause placenta mediated growth restriction?

Answer 16

Pre-eclampsia, smoking, alcohol, anaemia, malnutrition, infection

Question 17

What can cause non placenta mediated growth restriction?

Answer 17

Fetal pathologies, genetic abnormalities, structural abnormalities, fetal infection

Question 18

How can IUGR can be symmetrical or asymmetrical,

what causes asymmetrical IUGR?

Answer 18

Head grows, abdomen doesnt

This is because of placental insufficency

Question 19

How can IUGR be symmetrican what causes this?

Answer 19

Head and abdomen size reduce in parallel:

chromosomal abnormalities or infection

Question 20

Risk factors for SGA?

Answer 20

Previous SGA
Obesity
Smoking
Diabetes
Existing hypertension
Mother over 35

Low PAPP-A
Antiphospholipid syndrome

Question 21

What are the major maternal risk facrors for SGA?

Answer 21

Previous still birth > APLS > Renal disease

Assess for RFs: if one major or 3 minor RFs - reassess at 20 weeks

Question 22

When to assess for SGA at 20 weeks?

Answer 22

Assess for RFs: if one major or 3 minor RFs - reassess at 20 weeks

Question 23

What measurements /scan is done at 20 weeks to confirm SGA?

Answer 23

Foetal biometry - USS:

EFW (head circumference)
AC (Abdominal circumfrence)
Femur length

Question 24

What is done after the 20 W foetal biometry to also assess blood flow?

Answer 24

Fetal doppler of the umbilical artery Assess deoxygenated blood from fetus to mother If normal US every 2 weeks If abnormal US and doppler every week

Question 25

Signs of SGA?

Answer 25

Reduced amniotic fluid volume Abnormal doppler studies Reduced fetal movements Abnormal CTGs

Question 26

Investigations for SGA for low risk women?

Answer 26

Monitoring of symphysis fundal height at appontments from 24 weeks onwards if less than 10th centile picked up - serual growth scans and umbilical artery dopplier

Question 27

High risk women for SGA investigations?

Answer 27

Serial growth scans every 2 weeks with umbilical artery doppler and CTG

Question 28

What do serial US scans measure?

Answer 28

EFW (growth velocity) Abdominal circumferance (growth velocity) Umbilical arterial pulsatility index to measure flow through artery amniotic fluid volume

Question 29

What are the indications for immediate delivery for SGA?

Answer 29

Abnormal CTG Abnormal Doppler waveform (reversal of end-diastolic flow)

Question 30

How are SGA babies usually managed for delivery?

Answer 30

Deliver by 37 weeks so give corticosteroids if <36 weeks and MGsulphase if <30 weeks

Question 31

If at 20 weeks SGA is identified, how does monitoring decided?

Answer 31

Depends on the fetal doppler assessing deoxygenated blood from feotus to mother Normal = Serial Ultrasounds every 2 weeks 20-24 weeks Abnormal = serual ultrasound scan and ubilical artery doppler every week 26-28 weeks