Placenta
Gross / macroscopic variations and conditions
Variations in size and shape
Small / large for gestational age
Author: Mandolin S. Ziadie, M.D.
Last author update: 1 October 2011
Last staff update: 23 February 2021
Copyright: 2002-2023, PathologyOutlines.com, Inc.
PubMed Search: Low weight small for gestational age [title] placenta
Table of Contents
Small for gestational age | Large for gestational age | Microscopic (histologic) descriptionCite this page: Ziadie MS. Small / large for gestational age. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/placentalowweight.html. 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
