Fetal wellbeing, IUGR/SGA, FM Flashcards
Normal birth weight at term
2.5-4kg
(KKH cut off 3.6kg)
Low birth weight
<2.5kg
Very low birth weight
<1.5kg
Extremely low birth weight
<1kg
Definition of Small for Gestational Age (SGA)
Fetal abdominal circumference (AC) or estimated fetal weight (EFW) < 10th percentile for gestational age
- does NOT distinguish between constitutionally small or pathologically small fetuses
Constitutionally small fetuses
- Attain their genetic potential
- Small due to maternal parity, height, weight, ethnicity
- do NOT have poor perinatal outcomes
Definition of intra-uterine growth restriction
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
Types of growth restriction
- 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 - Symmetrical growth restriction
- prolonged period of poor growth in early pregnancy
Early FGR vs late FGR
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
Just remember: IUGR means AC or EFW < 3rd percentile
-
ALL IUGR is definitely SGA
but not all SGA is IUGR
-
Causes of IUGR
- Asymmetrical
- preeclampsia
- multiple pregnancies
- maternal smoking - 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
Suspected IUGR -> what to do?
- 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) - Appropriate counselling to patient and empower patient to assess fetal wellbeing
- Fetal movement charts - Surveillance
- Monitor every 1-2 weeks with U/S
Fetal wellbeing assessment: U/S doppler studies
ABNORMALITIES to look out for:
- Uterine artery >95th centile
- Umbilical artery >95th centile or absent/reversed end diastolic flow
- Middle cerebral artery <5th centile
Fetal wellbeing assessment: Liquor volume
*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
How to measure liquor volume/amniotic fluid?
Use of ultrasound to measure amniotic fluid index
- Normal AFI: 5-25cm
Oligohydramnios definition
AFI < 5cm
Causes of oligohydramnios
- 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) - Lower urinary tract obstruction
- PROM
- Maternal use of NSAIDs e.g. indomethacin
Polyhydramnios definition
AFI > 25cm
Causes of polyhydramnios
- Poorly controlled diabetes
*polyhydramnios + macrosomia = maternal DM until proven otherwise - Bowel atresia (Duodenal atresia in T21)
- Tracheal-oesophageal fistula
- Neuromuscular disorders
- Twin-twin transfusion syndrome
Fetal movements
- 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
How can mom assess fetal movements?
Use of fetal movement chart
Risk factors for stillbirth
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
Approach to reduced fetal movements
- 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 - Bedside liquor volume assessment OR formal scan for growth/liquor + dopplers if persistent/risk factors present
How can mummy assess for reduced FM on their own?
Lie on L lateral and count for 2h
- Normal: at least 10 movements within 2h
Normal fetal movements
- 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
