Intrauterine Growth Restriction (IUGR)
But in certain cases, babies in the womb are smaller than they should be. When this happens, it could be due to a condition known as intrauterine growth restriction, or IUGR.
The term IUGR refers to a condition in which a baby in the womb fails to grow at the expected rate during the pregnancy. In other words, at any point in the pregnancy, the baby is not as big as would be expected for how far along the mother is in her pregnancy (this timing is referred to as an unborn baby's "gestational age").
Babies who have IUGR often have a low weight at birth. If the weight is below the 10th percentile for a baby's gestational age (meaning that 90% of babies that age weigh more) the baby is also referred to as "small for gestational age," or SGA.
It's important to note that not all babies who are small for gestational age had IUGR while in the womb. Some are healthy babies who are just born smaller than average because their parents are small in stature.
The two types of IUGR are:
- In symmetrical IUGR, a baby's body is proportionally small. That means that all parts of the baby's body are similarly small in size.
- In asymmetrical IUGR, the baby has a normal-size head and brain but the rest of the body is small.
In many cases, IUGR is the result of a problem that prevents a baby from getting enough oxygen and nutrients. This lack of nourishment slows the baby's growth. It can happen for a number of reasons. A common cause is placental insufficiency, in which the tissue that delivers oxygen and nutrients to the baby is not attached properly or isn't working correctly.
Other possible causes during a woman's pregnancy include:
- certain behaviors, such as smoking, drinking alcohol, or abusing drugs
- exposure to infections (passed from the mother), such as cytomegalovirus, German measles (rubella), toxoplasmosis, and syphilis
- taking certain medications
- high blood pressure
- genetic disorders or birth defects
- living in high altitudes
Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.
© 1995-2009 The Nemours Foundation. All rights reserved.
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