children s health issues
Small for Gestational Age (SGA) Newborns
Introduction
A newborn who weighs less than 90% of newborns of the same gestational age at birth (below the 10th percentile) is considered small for gestational age. Newborns may be small because their parents are small, the placenta did not function normally, or the mother has a medical disorder, has taken certain medications, or has used illicit drugs, tobacco, or alcohol during the pregnancy. Unless they are born with an infection or have a genetic disorder, most small-for-gestational-age newborns have no symptoms and do well. Some small newborns remain small as adults. Gestational age refers to the number of weeks of pregnancy. The gestational age is determined by counting the number of weeks between the first day of the mother's last menstrual period and the day of delivery. This time frame is often adjusted according to other information doctors receive, including the results of early ultrasound scans, which give additional information regarding the gestational age. A baby is estimated to be due (the due date) at 40 weeks of gestation. At a gestational age of 40 weeks, boys who weigh less than about 6 pounds 9 ounces (3 kilograms) are small for gestational age. Girls who weigh less than about 6 pounds 3 ounces (2.8 kilograms) are small for gestational age. Doctors use growth charts to evaluate babies at other gestational ages. (See also Overview of General Problems in Newborns .) 