Birth Weight: What Low and High Birth Weight Mean for a Baby

What it is

Birth weight is a baby's first weight, taken just after birth.

Low birth weight

A baby may be born too small, too early (premature), or both. Causes include:

• health problems in the pregnant parent;
• certain medicines, substance use or infections during pregnancy;
• carrying more than one baby;
• problems with the placenta, the organ that brings the baby oxygen and nutrients;
• small parents;
• genetic conditions or birth defects in the baby.

Possible problems:

• right away — breathing problems, infections, low blood sugar (hypoglycemia), jaundice, and trouble keeping warm;
• later — delays in motor and social development, learning disabilities, and in adulthood a higher risk of heart disease, high blood pressure, diabetes and obesity.

High birth weight

Causes can include big parents, diabetes in the pregnant parent, certain genetic conditions, and gaining too much weight during pregnancy.

Possible problems: a large baby can make delivery difficult and raise the risk of birth injuries, and is at higher risk of problems with blood sugar, breathing and jaundice.

Prevention

You may be able to prevent some birth weight problems by:

• getting regular checkups during pregnancy;
• getting the right amount of nutrition and calories;
• controlling your blood sugar if you have diabetes;
• avoiding substance use during pregnancy.

Sources

Based on "Birth Weight," MedlinePlus, National Library of Medicine; a work of the United States government in the public domain.