Low birth weight
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.
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
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.