Definition
- SGA ≠ FGR
- SGA is baby less than 10th percentile in intergrowth 21 charts
- FGR is baby not attaining full growth potential due to environmental or genetic factors
consensus definition
| Early FGR | late FGR |
|---|---|
| <32 weeks in the absence of congential anomolies | >32 weeks in the absence of congenital anamolies |
| abdominal circumference/Estimated fetal wight <3rd centile or UA-AEDF or AC/EFW <10th centile combained with 1. UtA PI >95th centile and/or 2. UA PI >95th centile | AC/EFW <3rd centile or Atleast 2 or 3 1. AC/EFW <10th centile 2. AC/EFW crossing centiles >2 quartiles 3. CPR (cerebral perfusion ratio) < 5th centile or UA-PI 95th centile |
Types
| Asymmetric | 80% | occurs at later gestational age | reduced cell size |
|---|---|---|---|
| symmetric | 15% | occurs at earlier age, no evidence of placental disease | Reduced cell number |
| mixed | 5% | mix of two |
Pathogenesis
- reduction in umbilical blood flow - redistribution of blood from liver - reduction of abdominal circumference
- elevated placental resistance - decreased umbilical artery end-diastolic flow - increased pulsatility index - later can cause absent end-diastolic flow or reversed end-diastolic flow
- redirection of blood to vital organs - end-diastolic flow increases in cerebral arteries - brain sparing effect
difference between early FGR and late FGR
| Early FGR | late FGR |
|---|---|
| low prevalence (1-3%) | high prevalence (3-5%) |
| impaired trophoblastic invasion | impaired trophoblastic maturation |
| severe placental disease | mild placental disease |
| marked hypoxia | mild hypoxia |
| high morality, high morbidity | low mortality, high morbidity |
Causes
maternal
- <16 yrs or >36 yrs
- low socioeconomic status
- smoking, drug abuse
- diabetes mellitus
- maternal SLE
- use of assisted reproductive techniques
- chronic renal, gastric or gastrointestinal disease
Fetal
- chromosomal anomaly
- congenital malformation
- congenital infection
- multiple infection
Placental
- low placental weight
- placental infections
- placental mosaicism
- vascular anomalies
Endocrine
- insulin deficiency
- decreased IGF1,2, IGFBP-2
- endothelin deficiency
- reduced levels of thyroid hormones
Diagnosis
Clinical examination
Abdominal palpation
- limited value
symphysio-fundal height
- more than 3 weeks difference SFH and gestational age is specific marker for FGR
Fetal biometry
- abdominal circumference (reduction in AC is the first biometric marker)
- Biparietal diameter
- head circumference
- femur length
- HC/AC ratio
- estimated fetal weight
Doppler studies
- abnormal CPR and UtA velocities for late FGR
- UA velocities for early FGR
Management
Timing of delivery
- If Doppler velocity abnormalities are detected, baby can be delivered at any age after completion of steroids
Neonatal management
- High risk of short and long term complications
- 20-30% of recurrence in subsequent pregnancies
- feed to be started with high index of suspesion
short term complications
- hypoglycemia
- polycythemia
- hypocalcemia
- 3-4x higher risk of feed intolerance
- 2.5x higher risk of necrotizing enterocolitis
Long term complications
- 45% higher risk of BPD
- neurodevelopmental disabilities
- failure to thrive
- hypertension
- insulin resistance
- coronary artery disease
- cerebrovascular stroke
Prevention
- optimizing maternal age of delivery
- maternal nutrition
- micronutrient supplementation including calcium
- treatment of maternal diseases like gestational hypertension and diabetes
- cessation of smoking, alcohol and drug abuse
- Aspirin - inhibit platelet aggregation by enhancing nitric oxide - reduce uteroplacental resistance
- aspirin to be given in all women with risk factors of placental insufficiency or pre-eclampsia (81 gms from 12 to 28 weeks of gestation - preferably before 16 weeks)