Fetus is pathologically small (growth restricted)

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  Fetal growth restriction (FGR)

  
  
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  Intrauterine growth restriction

Small for gestational age

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  Fetus is small but healthy, not growth restricted

Most common cause of FGR is placental insufficiency

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  Estimated fetal weight (EFW) < 5th-10th percentile

  
  
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  Abdominal circumference (AC) < 5-10 percentile

  
  
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  Abnormal umbilical artery (UA) Doppler values

  
  
  
  
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    Initial ↑ systolic:diastolic (S:D) ratio

    
    
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    Eventual absent end diastolic flow

    
    
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    Final reversed end diastolic flow

  
  
  
  
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  Oligohydramnios

Other findings with FGR

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  Uterine artery postsystolic notch (early finding)

  
  
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  Ductus venosus shows reversed A-wave (late finding)

  
  
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  “Brain sparing” physiology (late finding)

  
  
  
  
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    Middle cerebral artery S:D ratio < UA S:D ratio

  
  

FGR associations

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  Twin-twin transfusion

  
  
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  Triploidy, trisomy 18, trisomy 13

  
  
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  Anomalies (such as gastroschisis)

Is pregnancy dated correctly

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  Cannot assess growth if dating is incorrect

FGR fetuses have 4x higher rates of adverse outcome

Good AC measurement necessary for accurate EFW

Well-performed biophysical profile testing is key

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  Determines risk for fetal acidosis and drives delivery plan

Perform UA Doppler at midcord level when fetus is at rest