Gross / macroscopic variations and conditions

Variations in size and shape

Small / large for gestational age

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Last staff update: 23 February 2021

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PubMed Search: Low weight small for gestational age [title] placenta

Mandolin S. Ziadie, M.D.
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Cite this page: Ziadie MS. Small / large for gestational age. website. Accessed June 1st, 2023.
Small for gestational age
  • Placental weight that falls below the 10th percentile for gestational age
  • Also called low weight placenta
  • Due to a variety of causes, including:
    • Fetal factors: prematurity, fetal malformations or trisomy, small for date fetus, neonatal high hemoglobin or lower than expected body size in later childhood for fetus
    • Maternal factors: low pregnancy weight gain, low maternal pregravid body weight, high maternal hemoglobin during pregnancy, gestational hypertension, paid employment during pregnancy, low parity, maternal diabetes, CMV, HSV or other chronic infections; other causes of reduced uteroplacental blood flow
Large for gestational age
  • Placenta weight > 90th percentile for estimated gestational age
  • Also called high weight placenta
  • Usually due to edema as a result of fetal or maternal factors
    • Fetal factors: acute antenatal hypoxia, including low Apgar scores, respiratory distress syndrome, neurologic abnormalities (may persist), hydrops / neonatal death (erythroblastosis fetalis, tumors or fetal renal vein thrombosis), chronic intrauterine infection, immunohemolytic anemia, fetomaternal hemorrhage and polyhydramnios (Hum Pathol 1987;18:387)
    • Maternal factors: diabetes, anemia, malnutrition, retroplacental hematoma and TORCH infections
  • Gross description: bulky, overweight placenta
  • Microscopic (histologic) description: may include extensive villous edema, chorangiosis and villous dysmaturity (distal villous hypoplasia)
Microscopic (histologic) description
  • Small for gestational age: evidence of placental hypoxia including terminal villous hypoplasia, chorangiosis or Tenney-Parker change
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