Intrauterine growth restriction

Intrauterine growth restriction (IUGR) or fetal growth restriction (FGR)  is defined as an estimated fetal weight (EFW)/abdominal circumference (AC) at one point in time during pregnancy being below 3^rd percentile or EFW/AC below the 10^th percentile for gestational age with deranged Doppler parameters ¹⁴.

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 intrauterine growth restriction ¹⁰.

Pathology

Etiology

IUGR can result from a vast number of causes:

• maternal conditions
  • maternal narcotics/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 syndrome)
    • chromosome 12p tetrasomy (Pallister-Killian syndrome)
  • confined placental mosaicism (CPM) ¹³
  • other syndromic anomalies
    • Cornelia de Lange syndrome
    • Neu-Laxova syndrome
    • Pena Shokeir syndrome
    • Seckel syndrome
    • Silver-Russel syndrome
    • Smith-Lemli-Opitz syndrome
  • in utero substance exposure
    • e.g. fetal hydantoin syndrome

Radiographic features

Antenatal ultrasound

Sonographic parameters include:

• non-Doppler features
  • reduced abdominal circumference (AC) and/or EFW
    • AC/EFW <3^rd percentile
    • AC/EFW <10^th percentile with deranged Doppler parameters
  • presence of oligohydramnios without ruptured membranes
  • increased head circumference (HC) to abdominal circumference (AC) ratio (in asymmetrical type)
  • advanced placental grade
• Doppler features: will require a chart to calculate absolute values
  • umbilical artery Doppler assessment
    • increased PI above 95^th percentile
    • absent/reversed diastolic flow
  • umbilical venous Doppler assessment
    • presence of pulsatility
  • uterine arterial Doppler assessment
    • increased mean uterine artery PI above 95^th percentile
    • presence of notching in mid to late pregnancy
  • CP ratio: reduced below 5^th percentile

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.

Complications

There are many including:

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

Differential diagnosis

General considerations include:

• incorrect dates

See also

• small for dates fetus