Fetal wellbeing, IUGR/SGA, FM

Question 1

Normal birth weight at term

Answer 1

2.5-4kg
(KKH cut off 3.6kg)

Question 2

Low birth weight

Answer 2

<2.5kg

Question 3

Very low birth weight

Answer 3

<1.5kg

Question 4

Extremely low birth weight

Answer 4

<1kg

Question 5

Definition of Small for Gestational Age (SGA)

Answer 5

Fetal abdominal circumference (AC) or estimated fetal weight (EFW) < 10th percentile for gestational age
- does NOT distinguish between constitutionally small or pathologically small fetuses

Question 6

Constitutionally small fetuses

Answer 6

• Attain their genetic potential
• Small due to maternal parity, height, weight, ethnicity
• do NOT have poor perinatal outcomes

Question 7

Definition of intra-uterine growth restriction

Answer 7

Fetus is unable to achieve its genetically determined potential for physical growth or expected in utero growth potential
- fetus at increased risk of perinatal morbidity and mortality
- AC or EFW < 3rd percentile

Question 8

Types of growth restriction

Answer 8

1. Asymmetrical growth restriction
   - placental insufficiency late in pregnancy with sparing of brain growth
   - HC/AC ratio is usually 1:1, if HC > AC: asymmetrical IUGR
2. Symmetrical growth restriction
   - prolonged period of poor growth in early pregnancy

Question 9

Early FGR vs late FGR

Answer 9

Early FGR
- <32 weeks
AC or EFW < 3rd percentile***
OR
AC or EFW <10th percentile AND either
- Uterine artery pulsatility index (UtA-PI)
- Umbilical artery pulsatility index (UAPI)

Late FGR
- 32 weeks or more
AC or EFW < 3rd percentile***
OR
At least 2/3 of the following:
- AC or EFW <10th percentile
- AC/EFW crossing >2 quartiles on growth centiles
- CPR <5th centile UA-PI >95th centile

Question 10

Just remember: IUGR means AC or EFW < 3rd percentile

Answer 10

-

Question 11

ALL IUGR is definitely SGA
but not all SGA is IUGR

Answer 11

-

Question 12

Causes of IUGR

Answer 12

1. Asymmetrical
   - preeclampsia
   - multiple pregnancies
   - maternal smoking
2. Symmetrical
   - small and normal
   - chromosomal disorder
   - congenital infection (TORCHES)
   - maternal drug or alcohol abuse
   - maternal chronic medical conditions:
   a. chronic hypertension
   b. long standing diabetes
   c. lupus anticoagulant

SAD PANTS PIM

Substance use (smoking, drugs, alcohol)
Age (extremes of maternal ages)
Diabetes

Placental insufficiency
Anomalies
Nutritional deficiency
Thyroid disorders
Syndromes

Pre-eclampsia
Infections (torch)
Multiple pregnancies

Question 13

Suspected IUGR -> what to do?

Answer 13

1. Assess other aspects of fetal well-being
   - U/S doppler studies
   - Liquor volume
   (asses fetal growth using U/S: head circumference, abdominal circumference, femur length)
2. Appropriate counselling to patient and empower patient to assess fetal wellbeing
   - Fetal movement charts
3. Surveillance
   - Monitor every 1-2 weeks with U/S

Question 14

Fetal wellbeing assessment: U/S doppler studies

Answer 14

ABNORMALITIES to look out for:
- Uterine artery >95th centile
- Umbilical artery >95th centile or absent/reversed end diastolic flow
- Middle cerebral artery <5th centile

Question 15

Fetal wellbeing assessment: Liquor volume

Answer 15

*Liquor volume is from baby’s pee
*Measuring liquor volume is a reflection of baby’s urine output and a measure of baby’s kidney function
*After 20 weeks, amniotic fluid is mostly made up of baby’s pee (liquor)

ABNORMALITIES
- Oligohydramnios
- Polyhydramnios

Question 16

How to measure liquor volume/amniotic fluid?

Answer 16

Use of ultrasound to measure amniotic fluid index
- Normal AFI: 5-25cm

Question 17

Oligohydramnios definition

Answer 17

AFI < 5cm

Question 18

Causes of oligohydramnios

Answer 18

1. Severe IUGR (leads to reduced renal perfusion)
   - baby is small -> o2 rich blood is redirected to brain, heart (rest of the end organs not as important)
2. Lower urinary tract obstruction
3. PROM
4. Maternal use of NSAIDs e.g. indomethacin

Question 19

Polyhydramnios definition

Answer 19

AFI > 25cm

Question 20

Causes of polyhydramnios

Answer 20

1. Poorly controlled diabetes
   *polyhydramnios + macrosomia = maternal DM until proven otherwise
2. Bowel atresia (Duodenal atresia in T21)
3. Tracheal-oesophageal fistula
4. Neuromuscular disorders
5. Twin-twin transfusion syndrome

Question 21

Fetal movements

Answer 21

• First perceived between 18-20 weeks
• <24 weeks = described as a flutter, ‘bowel gas’, ‘swish’
• 24 weeks and beyond = more pronounced kicks
• Significant reduction or sudden alteration may be associated with poor perinatal outcome -> stillbirth

Question 22

How can mom assess fetal movements?

Answer 22

Use of fetal movement chart

Question 23

Risk factors for stillbirth

Answer 23

Maternal
- Multiple consultations for reduced FM
- Hypertension
- Diabetes
- Extremes of maternal age
- Smoking
- Poor past obstetric history
- Poor antenatal follow up
- Domestic violence

Fetal
- Fetal growth restriction
- Congenital malformation
- Congenital infections
- Genetic abnormalities

Question 24

Approach to reduced fetal movements

Answer 24

1. History and stillbirth risk evaluation
   2a. Fetal heart rate on CTG if > 28W GA for at least 20 mins
   2b. Assess fetus using doppler if <28W GA
2. Bedside liquor volume assessment OR formal scan for growth/liquor + dopplers if persistent/risk factors present

Question 25

How can mummy assess for reduced FM on their own?

Answer 25

Lie on L lateral and count for 2h
- Normal: at least 10 movements within 2h

Question 26

Normal fetal movements

Answer 26

• Multiparous women usually start feeling from 16 weeks onwards
• Nullips usually start feeling at 18-20 weeks
• Frequency increases until 32 weeks, then plateaus till labour
• Average FM/h is ~30
• Anything >90mins with no FM is odd