Small/Large for Dates

Question 1

When do you classify a baby as Small for Gestational Age (SGA)?

What are the 4 options for SGA? (and include the growth velocity)

Answer 1

Usually when it is below the 10th decile of estimated fetal weight

Small for dates

1. Starved small (IUGR)- ↓growth velocity
2. Abnormally small (IUGR-chromosomal)- ↓growth velocity
3. Normally small (constitutionally small)-normal velocity
4. Wrong dates- normal velocity

Question 2

What is IUGR? How is it seen on charts?

Answer 2

IUGR-intrauterine growth restriction

-progressing well, then fall off chart (↓growth velocity when demand for blood increases due to PLACENTAL INSUFFICIENCY)

Question 3

What are some risk factors for ‘starved small’ IUGR

Answer 3

IUGR
Starved small (ASYMETRICAL-relativly bigger head)
-smoking/drugs/alcohol)
-maternal nutrition
-hypertension (and maternal comorbidities:cardiac/renal/SLE/preeclampsia)
-twins

Question 4

What are some risk factors for ‘abnormal small’ IUGR

Answer 4

IUGR 
Abnormal small (SYMETRICAL)
-chromosomal abnormality 
-infection (TORCH) 
-structural/genetic abnormality

Question 5

How can you tell the difference between starved small and abnormal small?

Answer 5

Both have ↓growth velocity

• starved small ASYMETRICAL-relativly bigger head
• abnormal smal SYMETRICAL-all small

Question 6

What factors might co-exist in the history for a woman with an IUGR baby?

Answer 6

• Previous small baby
• Antepartum haemorrhage
• Reduced fetal movements

Question 7

What measurements are made during ante-natal scanning that help us get a picture of babies size?

Answer 7

Abdominal circumference
Head circumference
Femur length
Bi-parietal diameter

Question 8

How do we tell the difference between constitutionally small babies and IUGR babies based on these measurements?

Answer 8

SLOWED RATE OF GROWTH - if serial growth plots are starting to cross the centiles then always be concerned about IUGR
HEAD SPARING - IUGR will have asymmetrical growth (the head is prioritised and remains normal size). In constitutionally small babies/abnormally small babies it is symmetrically small

Question 9

What is always important to ask a woman if her baby is small?

Answer 9

How much it is MOVING - if the baby is restricted it will attempt to preserve energy by being less active

Question 10

How can we check whether placental blood flow has anything to do with restriction?

Answer 10

DOPPLER ULTRASOUND OF UMBILICAL ARTERY

Question 11

What is the really important thing to look at on doppler ultrasound of the umbilical artery?

Answer 11

END-DIASTOLIC FLOW.
There should always be a positive pressure in the umbilical artery even at the end of maternal diastole. If there is not (if EDF is low or even reversed) then this is very suggestive that the baby is at risk of HYPOXIA and delivery should be considered

Question 12

What are babies with IUGR at risk of?

Answer 12

• Peri-natal mortality
• Still birth
• Operative delivery
• NEC
• Cerebral palsy
• Increased risk of diabetes and CHD

Question 13

How do we manage small babies?

Answer 13

If the baby’s abdominal is found to be <10 centile then go on and do an umbilical artery doppler

• Generally, try to get to 34 weeks.
• If you cant (EDF reversed or decreased)>admit for steroids and daily CTG> probs C section

Question 14

What are big babies also known as?

Answer 14

MACROSOMIC

Question 15

When do macrocosmic babies usually occur? Why?

Answer 15

In diabetic women.

-Fetal hyperinsulinaemia leads to increased growth and organomegaly> erythropoeisis > neonatal polycythaemia

Question 16

What are macrocosmic babies more at risk of?

Answer 16

Macrosomia risks

• Sudden intrauterine death
• Hypoxia/respiritory distress (increased oxygen demands)
• Shoulder dystocia at delivery
• Post birth neonatal hypoglycaemia (so used to high glucose)

(also hypocalcaemia, hypomagnesaemia and polycythaemia)