Intrauterine growth restriction describes a fetus whose weight is below the 10th percentile for gestational age.

Alternative Names

Intrauterine growth retardation; IUGR

Causes, incidence, and risk factors

Intrauterine growth restriction (IUGR) may be suspected if the size of the mother's uterus is small. The condition is usually confirmed by ultrasound . Several factors can cause poor growth of a fetus. Undernutrition of the fetus may occur as a result of insufficiency of the placenta, multiple pregnancies, heart disease in the mother, preeclampsia or eclampsia , and high altitude. Fetuses with congenital or chromosomal abnormalities are often associated with below-normal weight. Infections during pregnancy that affect the fetus, such as rubella , cytomegalovirus, toxoplasmosis , and syphilis , may also affect fetal weight. Risk factors in the mother that may contribute to intrauterine growth retardation include poor nutrition, heart disease or high blood pressure , smoking , drug addiction , and alcohol abuse . If the mother is small, it may be normal for her to have a small fetus, but this is not due to IUGR. Depending on the cause of IUGR, the fetus may be symmetrically small, or have a head that is normal size for gestational age, while the remainder of the fetus is growth restricted.

Signs and tests

Prenatal examination may show that the fetus is small for the gestational age (the size of the uterus is less than the expected size for the weeks of pregnancy ). Tests for prenatal infection, congenital anomalies, or chromosomal abnormalities may be performed if IUGR is suspected.

Treatment

Because IUGR fetuses are at higher risk for intrauterine death, prenatal surveillance of fetal well-being may be performed. This surveillance usually occurs by non-stress testing or serial fetal ultrasounds. Depending on the results of these tests, delivery may be indicated.

Expectations (prognosis)

The prognosis for normal newborn growth and development varies by the degree and cause of IUGR. Prognosis should be discussed with your obstetrician and pediatrician.

Complications

Depending on the specific cause, IUGR fetuses are at increased risk for a variety of pregnancy and newborn complications. They may display non-reassuring fetal heart rate tracings during labor. You should discuss potential complications with your obstetrician and pediatrician.

Calling your health care provider

Call your health care provider if you are pregnant and the fetus seems very small. Also call if an infant or child does not seem to be growing or developing normally.

Prevention

Control risk factors during pregnancy , when possible.