Small for Gestational Age

Question 1

What is meant by small for gestational age (SGA)?

Answer 1

An infant with a birth weight <10th centile for its gestational age

Question 2

What is severe SGA?

Answer 2

Birth weight <3rd centile

Question 3

What is fetal SGA?

Answer 3

An EFW or abdominal circumference <10th centile

Question 4

What is severe fetal SGA?

Answer 4

EFW or AC <3rd centile

Question 5

What is fetal growth restriction?

Answer 5

When a pathological process has restricted genetic growth potential

Question 6

How can fetal growth restriction present?

Answer 6

Fetal compromise, including reduced liquor volume or abnormal Doppler studies

Question 7

What is low birth weight?

Answer 7

An infant born with birth weight <2500g

Question 8

What can the pathophysiology of SGA be divided into?

Answer 8

• Constitutionally small
• Placenta mediated growth restriction
• Non-placenta mediated growth restriction

Question 9

What % of SGA foetuses/infants are constitutionally small?

Answer 9

50-70%

Question 10

How are constitutionally small foetuses identified?

Answer 10

Small size at all stages, but growth following the centiles

Question 11

What is the pathology in constitutionally small foetuses?

Answer 11

No pathology is present

Question 12

What are the contributing factors for constitutionally small foetuses?

Answer 12

• Ethnicity
• Sex
• Parental height

Question 13

How is placental mediated growth restriction identified?

Answer 13

Growth is normal initially, but slows in utero

Question 14

What are the maternal factors that can result in placental insufficiency?

Answer 14

• Low pre-pregnancy weight
• Substance abuse
• Autoimmune disease
• Renal disease
• Diabetes
• Chronic hypertension

Question 15

What can cause non-placenta mediated growth restriction?

Answer 15

• Chromosomal or structural abnormality
• Error in metabolism
• Fetal infection

Question 16

When should women be assessed for risk factors for SGA?

Answer 16

At booking, and again in 20 weeks

Question 17

What are the major risk factors for SGA?

Answer 17

• Maternal age >40
• Smoker 11 or more per day
• Previous SGA baby
• Maternal/paternal SGA
• Previous stillbirth
• Cocaine use
• Daily vigorous exercise
• Maternal disease
• Heavy bleeding
• Low PAPP-A

Question 18

What maternal disease is a risk factor for SGA?

Answer 18

• Chronic hypertension
• Renal impairment
• Diabetes with vascular disease
• Anti-phospholipid syndrome

Question 19

What is PAPP-A?

Answer 19

Pregnancy associated plasma protein

Question 20

What are the minor risk factors for SGA?

Answer 20

• Maternal age 35 or over
• Smoker 1-10/day
• Nulliparity
• BMI <20 or 25-34.9
• IVF singleton
• Previous pre-eclampsia
• Pregnancy interval <6 or >60 months
• Low fruit intake pre-pregnancy

Question 21

What is the role of ultrasound in SGA?

Answer 21

It is used for the diagnosis and surveillance of a SGA fetus

Question 22

What ultrasound biometrics can be used in the assessment of fetal size?

Answer 22

• EFW

- AC

Question 23

What is done with ultrasound biometrics to help determine fetal growth?

Answer 23

They are plotted on customised centile charts

Question 24

What do customised centile charts take into account?

Answer 24

• Maternal characteristics
• Gestational age
• Sex

Question 25

What maternal characteristics are taken into account on customised centile charts?

Answer 25

- Height - Weight - Ethnicity - Parity

Question 26

What ratio is important when assessing SGA?

Answer 26

Head circumference to AC

Question 27

Why is the head circumference to AC ratio important in SGA?

Answer 27

A symmetrically small fetus is more likely to be constitutionally small, whereas an asymmetrically small fetus is more likely to be caused by placental insufficiency

Question 28

What other ultrasound finding might be present in placental insufficiency?

Answer 28

Reduced amniotic fluid volume

Question 29

Why might there be a reduced amniotic fluid volume with placental insufficiency?

Answer 29

Placental insufficiency can result in impaired kidney function, which can cause reduced amniotic fluid volume

Question 30

What investigations may be appropriate in SGA?

Answer 30

- Detailed fetal anatomical survey - Uterine artery Doppler - Karyotyping - Screening for infections

Question 31

What infections should be screened for in SGA?

Answer 31

- CMV - Toxoplasmosis - Syphilis - Malaria

Question 32

How can SGA be prevented?

Answer 32

- Modification of risk factors | - Anti-platelet agents

Question 33

Give 2 examples of how risk factors can be modified to prevent SGA?

Answer 33

- Promoting smoking cessation | - Optimising maternal disease

Question 34

In whom might anti-platelet agents be effective at preventing SGA?

Answer 34

Women at high risk of pre-eclampsia

Question 35

When should anti-platelet agents be started in women at high risk of pre-eclampsia?

Answer 35

On or before 16 weeks of pregnancy

Question 36

What is the primary surveillance tool in a SGA fetus?

Answer 36

Uterine artery doppler

Question 37

What should be done if the uterine artery doppler is normal in a SGA fetus?

Answer 37

Repeat every 14 days

Question 38

What should be done if the uterine artery doppler is abnormal in SGA fetus?

Answer 38

Repeat more frequently, or consider delivery

Question 39

What other tests may be useful in the surveillance of a SGA fetus?

Answer 39

- Symphysis fundal height (SFH) - Middle cerebral artery (MCA) Doppler - Ductus venosus doppler - Cardiotocography - Amniotic fluid volume

Question 40

What should be given in SGA if delivery is being considered between 24 and 35+6 weeks gestation?

Answer 40

A single course of antenatal steroids

Question 41

What should be done if the fetus is <37 weeks and there is absent/reverse end-diastolic flow on Doppler?

Answer 41

Offer C-section

Question 42

What should be done if the fetus is SGA and 37 weeks?

Answer 42

Offer induction

Question 43

What is induction for SGA fetus associated with?

Answer 43

High rate of C-section

Question 44

What is required when inducing someone for SGA fetus?

Answer 44

Continuous fetal heart rate monitoring from onset of contractions

Question 45

What are the neonatal complications of SGA?

Answer 45

- Birth asphyxia - Meconium aspiration - Hypothermia - Hypo or hyperglycamia - Polycythaemia - Retinopathy of prematurity - Persistent pulmonary hypertension - Pulmonary haemorrhage - Necrotising enterocolitis

Question 46

What are the long-term complications of SGA?

Answer 46

- Cerebral palsy - Type 2 diabetes - Obesity - Hypertension - Precocious puberty - Behavioural problems - Depression - Alzheimer's - Cancer

Question 47

What cancers are more common in people that were SGA at birth?

Answer 47

- Breast - Ovarian - Colon - Lung - Blood