Small for gestational age, also known as intrauterine growth retardation, is defined as an infant or fetus smaller in size than expected, meaning a weight in the bottom tenth percentile for a particular age. Small for gestational age is believed to be related to placental insufficiency, infectious disease, congenital malformations, drug and alcohol abuse, and cigarette smoking. Other risk factors include maternal hypertension, first pregnancies, and exposure to environmental toxins. It is considered to be one cause of low birth weight (less than twenty-five hundred grams, or five pounds eight ounces). It is not synonymous with prematurity, which is defined as birth before thirty-seven-weeks gestation.
Mary Cowley Parke
Strauss, R. S. (2000). "Adult Functional Outcome of Those Born Small for Gestational Age: Twenty-Six Year Follow-Up of the 1970 British Birth Cohort." Journal of the American Medical Association 283:625–632.
Centers for Disease Control and Prevention (1994). "Low Birth Weight and Intrauterine Growth Retardation." In From Data to Action: Public Health Surveillance for Women, Infants, and Children. Available from <http://www.cdc.gov/nccdphp>
"Small-for-Gestational-Age Infant." Merck Manual. Available from <http://www.merck.com>