Low birth weight: What does it mean?

Low birth weight is a term used to describe babies who weigh less at birth than they should for their gestational age. Full-term babies who weigh less than 5 pounds, 4 ounces at birth are considered low birth weight.

Some low birth weight babies are healthy, even though they're small. They may be small simply because their parents are smaller than average. Other babies are low birth weight because something slowed or stopped their growth in the uterus.

Causes of low birth weight include:

• Smoking
• Poor nutrition
• Infection or illness in the mother or fetus
• Alcohol or drug abuse
• Certain placental problems
• Certain birth defects

In general, the lower the birth weight, the greater the risk of serious health problems.