Small and Large for Dates Pregnancies
Low birth weight (LBW) = infants with an absolute birth weight <2.5kg
Very low birthweight (VLBW) = infants with an absolute birth weight <1.5kg
Extremely low birthweight (ELBW) = infants with an absolute birth weight <1kg
Small for gestatonal age (SGA) = foetus <10th percentle for gestatonal age – not always pathological
Large for gestatonal age (LGA) = foetus >90th percentle for gestatonal age
Appropriate for gestatonal age (AGA) = foetus between 10th-90th percentle for gestatonal age
Intrauterine Growth Restricton (IUGR)
IUGR = foetus that fails to reach its full growth potental usually leading to SGA) - always pathological
Epidemiology
- 4-8% of foetuses are diagnosed with IUGR
Aetology
Foetal Uteroplacental Maternal
Genetc anomaly e.g. Placental abrupton Malnutriton
trisomy, single gene defect, Alcohol Foetal alcohol syndrome)
mosaicism) Velamentous cord inserts Smoking
into membranes not placenta) Drugs Cocaine, ACE-I, B-blocker, K-blocker)
Structural anomaly e.g. CV Infecton e.g. malaria, rubella. CMV, toxoplasmosis,
anomaly, bilateral renal Oligohydramnios (usually due varicella) - Malaria most common cause worldwide
agenesis) to renal agenesis or atresia or Maternal illness e.g. HTN, anaemia, APLS, COPD
ureter IUGR + clubbed feet hyperthyroid, cyanotc heart disease)
Multple pregnancy + pulmonary hypoplasia + Age >40
cranial anomalies) Prior IUGR infant
Pathophysiology
1) Compromise to uteroplacental blood fow
2) Decreased nutrient to foetus glucose, O2, amino acids, GF)
3) Diminishing of foetal growth subcut tssue > axial skeleton > vital organs)
4) Demands exceed supply to feto-placental unit
5) Foetal wastng and distress
Classificaton
- Symmetric IUGR 20%) – foetus is symmetrically small – Started in 1 st trimester thus long-term
compromise. Usually chromosomal.
- Asymmetric IUGR 80%) – foetal head is proportonately larger than the body. Started later in
development thus short-term compromise with ‘sparing’ of the brain. Usually placental problem or
maternal HTN.
Diagnosis
- O/E – Fundal height <3-4cm than expected
- Ultrasound biometry Gold Standard) – small estmated foetal weight using FL, AC and HC)
Management
- Identfy and manage underlying factors
- Nutritonal advice and bedrest not shown to help)
- Monitor with CTG weekly) and Serial USS every 2-4 weeks)
- Steroids for foetal lung development)
- Appropriately tmed delivery Expedite if necessary)
Complicatons - 50% will have neonatal morbidity such as –
- Polycythaemia causing hyperviscocity and increased risk of thrombus)
o Renal vein thrombosis
o Mesenteric thrombosis NEC
- Loss of subcut fat and glycogen stores
o Hypothermia
o Hypoglycaemia
- Pulmonary haemorrhage
- Meconium aspiraton syndrome
Low birth weight (LBW) = infants with an absolute birth weight <2.5kg
Very low birthweight (VLBW) = infants with an absolute birth weight <1.5kg
Extremely low birthweight (ELBW) = infants with an absolute birth weight <1kg
Small for gestatonal age (SGA) = foetus <10th percentle for gestatonal age – not always pathological
Large for gestatonal age (LGA) = foetus >90th percentle for gestatonal age
Appropriate for gestatonal age (AGA) = foetus between 10th-90th percentle for gestatonal age
Intrauterine Growth Restricton (IUGR)
IUGR = foetus that fails to reach its full growth potental usually leading to SGA) - always pathological
Epidemiology
- 4-8% of foetuses are diagnosed with IUGR
Aetology
Foetal Uteroplacental Maternal
Genetc anomaly e.g. Placental abrupton Malnutriton
trisomy, single gene defect, Alcohol Foetal alcohol syndrome)
mosaicism) Velamentous cord inserts Smoking
into membranes not placenta) Drugs Cocaine, ACE-I, B-blocker, K-blocker)
Structural anomaly e.g. CV Infecton e.g. malaria, rubella. CMV, toxoplasmosis,
anomaly, bilateral renal Oligohydramnios (usually due varicella) - Malaria most common cause worldwide
agenesis) to renal agenesis or atresia or Maternal illness e.g. HTN, anaemia, APLS, COPD
ureter IUGR + clubbed feet hyperthyroid, cyanotc heart disease)
Multple pregnancy + pulmonary hypoplasia + Age >40
cranial anomalies) Prior IUGR infant
Pathophysiology
1) Compromise to uteroplacental blood fow
2) Decreased nutrient to foetus glucose, O2, amino acids, GF)
3) Diminishing of foetal growth subcut tssue > axial skeleton > vital organs)
4) Demands exceed supply to feto-placental unit
5) Foetal wastng and distress
Classificaton
- Symmetric IUGR 20%) – foetus is symmetrically small – Started in 1 st trimester thus long-term
compromise. Usually chromosomal.
- Asymmetric IUGR 80%) – foetal head is proportonately larger than the body. Started later in
development thus short-term compromise with ‘sparing’ of the brain. Usually placental problem or
maternal HTN.
Diagnosis
- O/E – Fundal height <3-4cm than expected
- Ultrasound biometry Gold Standard) – small estmated foetal weight using FL, AC and HC)
Management
- Identfy and manage underlying factors
- Nutritonal advice and bedrest not shown to help)
- Monitor with CTG weekly) and Serial USS every 2-4 weeks)
- Steroids for foetal lung development)
- Appropriately tmed delivery Expedite if necessary)
Complicatons - 50% will have neonatal morbidity such as –
- Polycythaemia causing hyperviscocity and increased risk of thrombus)
o Renal vein thrombosis
o Mesenteric thrombosis NEC
- Loss of subcut fat and glycogen stores
o Hypothermia
o Hypoglycaemia
- Pulmonary haemorrhage
- Meconium aspiraton syndrome
