Macrosomia Differential Diagnoses

Updated: Dec 16, 2020
  • Author: Easha A Patel, MD; Chief Editor: Christine Isaacs, MD  more...
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Diagnostic Considerations

Important considerations

Problems associated with overdiagnosis:

  • Delivery of an immature fetus for suspected macrosomia

  • Surgical complications due to a prophylactic cesarean delivery for suspected macrosomia due to inaccurate ultrasound-based estimated fetal weight in a newborn that has appropriate growth for gestational age

  • Surgical complications due to prophylactic cesarean delivery for suspected macrosomia when the frequency of shoulder dystocia is low, the risk of brachial plexus injury is lower, and the risk of permanent brachial plexus injury is lower still

Problems associated with underdiagnosis:

  • Shoulder dystocia in a newborn delivered by operative vaginal delivery found to be macrosomic at birth

  • Shoulder dystocia and permanent nerve injury in a macrosomic fetus

  • Failure to diagnose macrosomia and birth injury at delivery

  • Use of incorrect maneuvers for releasing shoulder dystocia in a macrosomic newborn


Consider the following conditions in the differential diagnosis in patients with suspected macrosomia on physical exam:

  • Polyhydramnios

  • Inaccurate gestational age

  • Multiple gestations

  • Pelvic masses

  • Fibroid uterus

Consider the following as possible contributors to macrosomia:

  • Diabetes Mellitus

  • Maternal obesity

  • Excessive gestational weight gain

  • Post-term pregnancy

  • Macrosomia due to genetics and relationship to parental stature.

Differential Diagnoses