Newborn with birth weight > 4,000 or 4,500 g (10 lb)

Fetus is considered at risk for macrosomia if estimated fetal weight (EFW) is > 90th percentile

Large abdominal circumference (AC) is 1st clue

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  AC is heavily weighted in all EFW calculations

Unfortunately, fetal weight prediction is not very accurate

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  High false-positive rates for macrosomia

  
  
  
  
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    Only 1/2 of newborns predicted to weigh > 4,500 g will actually weigh > 4,500 g

  
  
  
  
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  High negative predictive value of 97-99% is reassuring

  
  
  
  
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    EFW < 90th percentile is usually predictive that newborn will not be macrosomic

  
  
  
  
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  Growth graphs are useful visual tools

Associated findings

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  Polyhydramnios

  
  
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  ↑ subcutaneous adipose tissue

Beckwith-Wiedemann syndrome: Large tongue, liver, spleen, kidneys

Hydrops: Skin edema, pleural effusion, ascites

Associated with maternal diabetes

Maternal complications: Prolonged, arrested labor

Fetal complications: Shoulder dystocia, hypoglycemia, hypocalcemia

Cesarean delivery recommended if EFW > 5,000 g and patient is not diabetic

Cesarean delivery recommended if EFW > 4,500 g and patient is diabetic

Perform several AC measurements and average good ones

Macrosomia is critical finding, just like fetal growth restriction (need to alert referring clinician)