Low birthweight in newborns
During pregnancy, a baby's birthweight can be estimated in different ways.
- The height of the fundus (the top of a mother's uterus) can be measured from the pubic bone. This measurement in centimeters usually corresponds with the number of weeks of pregnancy after the 20th week. If the measurement is low for the number of weeks, the baby may be smaller than expected.
- Ultrasound (a test using sound waves to create a picture of internal structures) is a more accurate method of estimating fetal size. Measurements can be taken of the fetus' head and abdomen and compared with a growth chart to estimate fetal weight.
Babies are weighed within the first few hours after birth. The weight is compared with the baby's gestational age and recorded in the medical record. A birthweight less than 5 pounds, 8 ounces is diagnosed as low birthweight. Babies weighing less than 3 pounds, 5 ounces at birth are considered very low birthweight.