Intrauterine growth restriction

Intrauterine growth restriction (IUGR) is commonly defined as an estimated fetal weight (EFW) at one point in time during pregnancy being at or below the 10^th percentile for gestational age ².

Some authors define the term IUGR when fetal biometric parameters fall under the 5^th percentile or fall below two standard deviations ¹².

Some authors consider this definition synonymous with the term small for gestational age (SGA).

An IUGR can be broadly divided into two main types:

• type I: symmetrical intrauterine growth restriction
• type II: asymmetrical intrauterine growth restriction

Some authors also enlist a 3^rd type termed: femur sparing-sparing intrauterine growth restriction ¹⁰.

Epidemiology

By its standard definition itself, it carries a prevalence of 10% of all births (if the 5^th centile is used it will affect 5% of all births instead).

Pathology

Causes

IUGR can result from a vast number of causes:

• maternal conditions
  • maternal narcoticnarcotics/smoking
  • maternal alcohol use : fetal alcohol syndrome
  • maternal diabetes: when severe maternal diabetes, there can be a paradoxical IUGR as opposed to fetal macrosomia
  • maternal malnutrition/starvation
  • maternal vascular conditions
  • certain medications
• placental insufficiency: commonest cause overall
  • abnormal uteroplacental circulation
  • abnormal fetoplacental circulation
• other placental causes
  • increased incidence with a single umbilical artery
• fetal conditions
  • multifetal pregnancy
  • intrauterine infections
  • chromosomal anomalies
    • trisomy 13
    • trisomy 18
    • triploidy: IUGR is of early onset
    • Down syndrome: not a dominant feature
    • chromosome 4p deletion syndrome (Wolf-Hirschhorn Syndromesyndrome)
    • chromosome 12p tetrasomy (Pallister-Killian Syndromesyndrome)
  • confined placental mosaicism (CPM) ¹³
  • other syndromic anomalies
    • Cornelia de Lange Syndromesyndrome
    • Neu-Laxova syndrome
    • Pena Shokeir syndrome
    • Seckel syndrome
    • Silver-Russel Syndromesyndrome
    • Smith-Lemli-Opitz syndrome
  • in utero substance exposure
    • e.g. fetal hydantoin syndrome

Radiographic features

Antenatal ultrasound

Sonographic parameters include:

• non-Doppler features
  • presence of oligohydramnios without ruptured membranes
  • increased head circumference (HC) to abdominal circumference (AC) ratio (in asymmetrical type)
  • decreased total intrauterine volumes
  • advanced placental grade
• Doppler features: will require a chart to calculate absolute values
  • umbilical artery Doppler assessment
    • increased S/D ratio(s)
    • increased resistive index (RI)
  • umbilical venous Doppler assessment
    • presence of pulsatility
  • uterine arterial Doppler assessment
    • presence of notching in mid to late pregnancy
    • increased S/D ratio(s)

Complications

TheyThere are many which includeincluding:

• antepartum 
  • stillbirth
  • iatrogenic prematurity
  • abruption
  • perinatal stroke 
• intrapartum
  • abnormal fetal status (fetal heart rate tracing) 
  • asphyxia 
  • emergency Caesarean section 
  • need for active neonatal resuscitation 
  • perinatal stroke 
• neonatal 
  • hypothermia 
  • hypoglycemiahypoglycaemia 
  • hypocalcemiahypocalcaemia 
  • polycythemiapolycythaemia 
  • sepsis 
  • coagulopathy 
  • hepatocellular dysfunction 
  • respiratory distress syndrome
  • necrotizing enterocolitis
  • intraventricular hemorrhagehaemorrhage, especially in premature IUGR neonates < 750;750 g 
  • hypoxic-ischemic-ischaemic encephalopathy
• paediatric
  • increased risk of: 
    • short stature 
    • cerebral palsy 
    • developmental delay 
    • behavioural and emotional problems 
    • lower IQ scores 
    • chronic lung disease 
    • future cardiovascular disease and hypertension

Treatment and prognosis

While there is no cure, management is reliant on a structured antenatal surveillance program with timely intervention in order to minimize fetal compromise.

Differential diagnosis

General considerations include:

• incorrect dates

See also

• small for dates fetus