Alternate Names: Small for gestational age; Dysmaturity; Low birth weight

Causes and Risks:

A low birth weight may be suspected before delivery if the size of the mother’s uterus is small, or if a small fetus is shown by ultrasound. Although the overall size of the infant is small, the organ systems are mature for age. Several factors can cause delayed 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. Babies with congenital anomalies or chromosomal abnormalities are often associated with a below-normal birth weight. Infections during pregnancy that affect the fetus, such as rubella, cytomegalovirus, toxoplasmosis, and syphilis, may also affect the birth weight. Risk factors in the mother that may contribute to intrauterine growth retardation include multiple gestation, 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 .

The fetus may be symmetrically small, or have a head that is normal size for gestational age and an abnormally small abdomen, depending on what stage of development the fetus has reached when growth retardation begins.

Prevention:

Control risk factors during pregnancy, when possible.

Symptoms:

• currently pregnant with a feeling that the baby is not as big as it should be
• infant is a small size for age but other physical characteristics are normal

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).

Newborn physical examination reveals a weight below the 10th percentile for age. The length and head size may be below the 10th percentile for age. Values below the 10th percentile indicate growth retardation.

Tests for prenatal infection may be performed if growth retardation is suspected before a baby is born.

Treatment:

There is no specific treatment. An adequate calorie intake should be maintained in these infants.

Prognosis:

There is a poorer long-term outlook for general development in infants with intrauterine growth retardation. There may be "catch up" growth in infants whose growth retardation was caused by malnutrition.

Complications:

• Birth asphyxia, or lack of oxygen during the birthing process, may occur if the growth retardation is due to insufficiency of the placenta.
• Meconium aspiration (aspiration of amniotic fluid that is contaminated with the infant’s first stool) may occur as a result of stress during delivery.
• There may be low blood glucose levels during the first hours or days of life.

Call for an appointment with the health care provider if you are pregnant and the baby seems very small.

Also call if an infant or child does not seem to be growing or developing normally.