The fetus may be pathologically small due to maternal, fetal or placental factors – e.g.
Maternal factors
• poor nutritional status, anaemia, recent pregnancy
• smoking, alcohol and/or drug use
• hypertension
• diabetes
• pulmonary, cardiovascular or renal disease
Fetal Factors
• chromosomal abnormalities
• intrauterine infection
Utero-placental
• placental disease/dysfunction
• multiple pregnancy
• uterine malformations
3. Royal College of Obstetricians and Gynaecologists The Investigation and management of the Small-for-Gestational Age Fetus:
Green-top Guideline No. 31: 2nd Edition. RCOG 2013 https://www.rcog.org.uk/globalassets/documents/guidelines/gtg_31.pdf