Small for gestational age (SGA)
Small for gestational age means that a fetus or an infant is smaller or less developed than normal for the baby's sex 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.
Low birth weight
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, and more)
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
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.
Suhrie KR, Tabbah SM. High-risk pregnancies. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 114.