Small for gestational age

Question 1

Define small for gestational age

Answer 1

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

Question 2

Define severe small for gestational age

Answer 2

A birth weight <3rd centile

Question 3

Define foetal SGA

Answer 3

An estimated foetal weight or abdominal circumference <10th centile

Question 4

Define foetal growth restriction

Answer 4

When a pathological process has restricted genetic growth potential

Question 5

What can foetal growth restriction present with?

Answer 5

Features of foetal compromise including reduced liquor volume or abnormal doppler studies

Question 6

What does low birth weight refer to?

Answer 6

An infant with birth weight <2500g

Question 7

List some causes for an infant/foetus being small for gestational age

Answer 7

Normal (constitutionally) small

Placenta mediated growth restriction

Non-placenta mediated growth restriction

Question 8

What percentage of SGA fetuses/infants are constitutionally small?

Answer 8

50-70%

Question 9

Describe constitutionally small fetus/infants

Answer 9

Small size at all stages but growth following centiles

No pathology present

Question 10

What contributes to a fetus/infant being constitutionally small?

Answer 10

Ethnicity
Sex
Parental height

Question 11

Describe placenta mediated growth restriction

Answer 11

Growth is usually normal initially but slows in utero

Placental insufficiency

Question 12

Give some maternal factors which can result in placental insufficiency

Answer 12

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

Question 13

Describe non-placenta mediated growth restriction

Answer 13

Growth is affected by foetal factors such as a chromosomal or structural anomaly - error in metabolism or foetal infection

Question 14

List some risk factors for small for gestational age

Answer 14

Maternal age >40
Smoker >11/day
Previous SGA baby 
Maternal/paternal SGA
Previous stillbirth
Cocaine use
Daily vigorous exercise
Maternal disease - Chronic hypertension, renal impairment, diabetes with vascular disease and antiphospholipid syndrome 
Heavy bleeding

Question 15

When are women assessed for risk factors for SGA

Answer 15

At booking and again at 20 weeks gestation

Question 16

How is SGA diagnosed?

Answer 16

Ultrasound - ratio of head circumference and abdominal circumference may be significant

Question 17

What is symmetrically small foetus most likely caused by?

Answer 17

Constitutional

Question 18

What is asymmetrically small foetus most likely caused by?

Answer 18

Placental insufficiency

Question 19

What can placental insufficiency result in?

Answer 19

Impaired foetal renal function and reduced amniotic fluid

Question 20

What other investigations may be useful in SGA?

Answer 20

Detailed foetal anatomical survey

Uterine artery doppler

Karyotyping

Screening for infections - congenital cytomegalovirus, toxoplasmosis, syphilis and malaria

Question 21

How is SGA prevented?

Answer 21

Modifying risk factors - promote smoking cessation and optimise maternal disease

Question 22

What drug should women at high risk of pre-eclampsia be started on and when?

Answer 22

75mg aspirin 16 weeks gestation until delivery

Question 23

How is SGA monitored?

Answer 23

Uterine artery doppler is primary surveillance tool - if normal repeat every 14days

Symphysis fundal height

Middle cerebral artery doppler

Ductus venosus doppler

CTG

Amniotic fluid volume

Question 24

What should be given if delivery between 24-35+6 weeks gestation is considered?

Answer 24

Single dose antenatal steroids

Question 25

Before 37 weeks what would be an indication for delivery and which mode of delivery would be used?

Answer 25

Absent/reverse end diastolic flow on doppler | C-section

Question 26

By 37 weeks what would be an indication for delivery and which mode of delivery would be used?

Answer 26

Abnormal UAD or MCA doppler | Induction

Question 27

At 37 weeks what would be an indication for delivery and which mode of delivery would be used?

Answer 27

Normal UAD | Induction

Question 28

What monitoring is required during labour after onset of contractions and why?

Answer 28

CTG - continuous foetal heart rate monitoring as high rate of C-sections

Question 29

List the neonatal complications of SGA

Answer 29

``` Birth asphyxia Meconium aspiration Hypothermia Hypo/hyperglycaemia Polycythaemia Retinopathy of prematurity Persistent pulmonary hypertension Pulmonary haemorrhage Necrotising enterocolitis ```

Question 30

List the long term complications of SGA

Answer 30

``` Cerebral palsy T2DM Obesity Hypertension Precocious puberty Behavioural problems Depression Alzheimer's disease Cancer - breast, lung, ovarian, colon and blood ```