Small for gestational age
How is small for gestational age (SGA) diagnosed?
SGA is often identified before birth. During pregnancy, a baby's size 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, your baby may be smaller than expected.
Although many SGA babies have low birthweight, they are not all premature and may not experience the problems of premature babies. Other SGA babies, especially those with IUGR, appear thin, pale and have loose, dry skin. The umbilical cord is often thin, and dull-looking rather than shiny and fat. They sometimes have a wide-eyed look.
Other diagnostic procedures may include the following:
- Ultrasound - 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. The fetal abdominal circumference is a helpful indicator of fetal nutrition.
- Doppler flow- Another way to interpret and diagnose IUGR during pregnancy is Doppler flow, which use sound waves to measure blood flow. The sound of moving blood produces wave-forms that reflect the speed and amount of the blood as it moves through a blood vessel. Blood vessels in the fetal brain and the umbilical cord blood flow can be checked with Doppler flow studies.
- Mother's weight gain - A mother's weight gain can also indicate a baby's size. Small maternal weight gains in pregnancy may correspond with a small baby.
- Gestational assessment- Babies are weighed within the first few hours after birth. The weight is compared with your baby's gestational age and recorded in the medical record. The birthweight must be compared to the gestational age. Some physicians use a formula for calculating a baby's body mass to diagnose SGA.