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Fetal Growth Restriction

From Mediwikis


A fetus whose weight falls below the 10th centile for gestational age has Fetal Growth Restriction (FGR, previously Intrauterine Growth Restriction). The small size may simply be a reflection of a small baby who is healthy (e.g. genetically small due to small parents) but there is often an underlying pathology. Babies with FGR have a ten-fold higher perinatal morbidity and mortality risk.
If growth is symmetrically restricted (head circumference is similar to abdominal circumference) then the cause is most likely poor maternal nutrition or it is a normal, genetically small baby.
Asymmetrical growth retardation (typically the head circumference is greater than the abdominal circumference) is a much more worrying sign, this is normally due to poor placental perfusion. Classically, ultrasound scans in the 3rd trimester show a normal increase in the head circumference with an abdominal circumference, which progressively falls away from the 10th centile. This head sparing growth retardation is often associated with the placental insufficiency of pre eclampsia.


  • Idiopathic
  • Normal variant (small parents)
  • Placental insufficiency:
  • Maternal malnutrition
    • Maternal alcoholism
    • Poor diet
    • Eating disorders
  • Fetal factors
    • Multiple pregnancy
    • Intra-uterine infection
    • Chromosomal abnormalities

Causes of symmetrical FGR

  • Idiopathic
  • Chromosomal abnormalities
  • ‘TORCH” infections - Toxoplasmosis, Other infections (HIV, syphilis, coxsachie, varicella), Rubella, CMV, Herpes type 2
  • Maternal smoking
  • Maternal alcohol/opiate abuse
  • Chronic maternal nutritional deficiency
  • Ionising radiation
  • Sickle cell disease

Causes of asymmetrical FGR

  • Idiopathic
  • Pre-eclampsia
  • Maternal renal or cardiac disease
  • Multiple gestation

Clinical features of baby

  • Cachexia
  • Polycythaemia
  • Dark, thick hair
  • Mature ears, breast tissue and genetalia
  • Good muscle tone
  • Loose, dry, thick skin


  • Failure of fetus and uterus to grow at the normal rate over a 4 week period
  • Symphyseal fundal height >2 cm less than expected of gestation
  • Poor maternal weight gain, inadequate or decreasing
  • Diminished fetal movements


  • Increased risk of intrauterine death
  • Increased risk of birth asphyxia
  • Hypothermia
  • Meconium aspiration
  • Hypoglycaemia (particularly in first few days of life; four hourly estimations of blood glucose should be made with early generous feeding)
  • Polycythaemia with increased risk of neonatal jaundice
  • 10% have associated congenital abnormalities
  • Thermoregulation problems
  • Pulmonary haemorrhage
  • Rickets


  • An ultrasound scan must be performed to determine whether baby is small for dates – SFH is inaccurate.
  • If growth is restricted; serial growth scans at fortnightly intervals, measuring and plotting head and abdominal circumference.
  • Perform umbilical artery Doppler scans.
  • Look for chromosomal abnormalities and assess for maternal infection
  • Consider early delivery – induced early labour vs. keeping baby to grow in potentially hostile environment. If >36 weeks induce labour.
  • Give steroids early (to encourage surfactant production to mature respiratory system) in case of spontaneous preterm labour.

After birth:

  • Four hourly estimations of blood glucose should be made with early generous feeding due to hypoglycaemia risk.

Risk in adult life

  • Coronary artery disease
  • Hypertension
  • Type 2 DM
  • Autoimmune thyroid disease