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The information contained on this page is provided as general health information and is not intended to substitute as medical advice and direction from your physician or health care provider. Please direct any questions related to your health care provider. In an emergency, call 9-1-1 or go to the nearest emergency center.


Small for gestational age (SGA)

Definition

Small for gestational age means that a fetus or an infant is smaller or less developed than normal for the baby's gender and gestational age. Gestational age is the age of a fetus or baby that starts on the first day of the mother's last menstrual period.

Alternative Names

Low birth weight

Information

Ultrasound is used to find out if a fetus is smaller than normal for their age. This condition is called intrauterine growth restriction. The most common definition of small for gestational age (SGA) is a birth weight that is below the 10th percentile.

Causes for SGA fetus may include:

  • Genetic diseases
  • Inherited metabolic diseases
  • Chromosome anomalies
  • Multiple gestations (twins, triplets, etc)

A developing baby with intrauterine growth restriction will be small in size and can have problems such as:

  • Increased red blood cells
  • Low blood sugar
  • Low body temperature

References

Baschat AA, Galan HL. Intrauterine growth restriction. In: Gabbe SG, Niebyl JR, Simpson JL, et al, eds. Obstetrics: Normal and Problem Pregnancies. 7th ed. Philadelphia, PA: Elsevier; 2017:chap 33.

Carlo WA. The high-risk infant. In: Kliegman RM, Stanton BF, St. Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 97.