Small-for-Gestational-Age Baby

(Intrauterine Growth Restriction)

Reviewed/Revised Nov 2023
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What is a small-for-gestational-age (SGA) baby?

Small-for-gestational-age (SGA) is a term used to describe a baby who is smaller than most babies. Gestational age is how far along the pregnancy is, measured in weeks. It's important to compare weight by gestational age because the earlier a baby is born, the smaller it normally is. It's also important to compare babies of the same sex because girls tend to be a bit smaller than boys. So, babies who weigh less than 9 out of 10 babies of the same sex at the same gestational age are SGA.

  • Some babies are SGA just because it runs in their family

  • Other babies are SGA because some problem kept them from growing as much as they should've in the womb (growth restriction)

  • Problems that can cause a baby to be SGA include placenta problems, using drugs during pregnancy, health problems in the mother or fetus, and lack of medical care during pregnancy

  • Most SGA babies look like other babies born at the same gestational age, just smaller

  • Most SGA babies catch up on their growth by age 1 year and reach the adult height they normally would

  • Babies whose growth was restricted in the womb because of a serious problem are more likely to have problems later on

What causes a baby to be small for gestational age?

Most SGA babies have no problems—they just happen to be small. Often lots of other people in their family are small too.

Many things raise the chances of having an SGA baby:




What are the symptoms of a baby being small for gestational age?

At full term (born at 39 or 40 weeks of pregnancy), SGA boys weigh less than about 6 pounds 9 ounces (3000 grams), and SGA girls weigh less than about 6 pounds 3 ounces (2800 grams).

Otherwise, SGA babies tend to look the same as other babies the same gestational age unless their growth was severely restricted. Then they may:

  • Look thin

  • Have less muscle and fat

  • Have sunken facial features

  • Have a small, thin umbilical cord

What complications do small-for-gestational-age babies have?

Depending on the underlying problem, SGA babies have a higher risk of complications such as:

  • Miscarriage or stillbirth

  • Trouble breathing and low oxygen levels

  • Low blood sugar

  • Trouble keeping a constant body temperature

  • Infection

How can doctors tell if my baby is small for gestational age?

Doctors weigh and measure your baby and:

  • Compare your baby's weight and length to others of the same gestational age and sex using standard growth charts

How do doctors treat babies who are small for gestational age?

Small babies who are healthy do not need any treatment.

Doctors will treat any complications that develop. Your baby may need:

  • Fluids given through your baby’s vein

  • Sugar through a vein or frequent feedings to treat low blood sugar

  • Sometimes, shots of growth hormone if your child is still small at 2 to 4 years old

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