Low birthweight
Summary
What is low birthweight?
Low birthweight is when a baby is born weighing less than 5 pounds, 8 ounces. Some babies with low birthweight are healthy, even though they’re small. But having a low weight at birth can cause serious health problems for some babies. A baby who is very small at birth may have trouble eating, gaining weight and fighting off infections. Some may have long-term health problems, too. About 1 in 12 babies (about 8 percent) in the United States is born with low birthweight.
What causes a baby to have a low birthweight?
There are two main reasons:
- Preterm birth.
- Fetal growth restriction (also called intrauterine growth restriction or small for gestational age). This means a baby doesn’t gain the weight they should before birth. Some babies may have low birthweight simply because their parents are small. Others may have low birthweight because something slowed or stopped their growth during pregnancy. Your health care provider measures your belly and uses ultrasound to help track your baby’s growth during pregnancy. Ultrasound uses sound waves and a computer screen to show a picture of your baby while you’re pregnant.
If your provider thinks your baby’s growth is being restricted, you may have ultrasounds more often (every 2 to 4 weeks) to track your baby’s growth. Your provider also may do other tests such as heart rate monitoring and tests to check for infections or birth defects. Babies who have birth defects are more likely to be born too early.
Source: March of Dimes (2021). Low Birthweight.