Intrauterine growth restriction (IUGR) is a medical term which refers to a baby who is not growing normally within the womb. In general, this label is for babies who weigh less than the 10th percentile for their gestational age, or period of pregnancy.
About a third of these babies are genetically abnormal. However, in about 40 percent of cases, no cause at all is identifiable.
IUGR is a serious complication of pregnancy because it is the second leading cause of low birth weight. Again, these children have a risk of death which is about eight times higher than for normal babies. For this reason, much effort is needed to find the cause and treat it if possible, and facilitate a non-traumatic delivery at the right time.
This condition may occur for a variety of causes, such as:
- A placenta which is not functioning properly to supply food and oxygen to the baby
- Pregnancy at too high an altitude which deprives the blood of sufficient oxygen for the baby’s growth
- Pregnancy with twins or even more babies which means they have to share nutrients and oxygen
- Preeclampsia and eclampsia, conditions which are associated with high blood pressure in pregnancy, and which lead to poor growth or even death of the baby inside the womb
- Infections during pregnancy such as cytomegalovirus, syphilis or German measles
- Defective or chromosomally abnormal babies may lack the mechanisms necessary for proper growth
- Poor habits such as drinking too much or smoking, or doing drugs, while pregnant – smoking is associated with over a third of all cases of IUGR
- Medical conditions of the mother
Sometimes it is possible to tell what kind of condition is causing the IUGR, because lack of food causes the baby to have a normal head size but a small thin body. On the other hand, a baby who is small all over is often suffering from the results of infection, or congenital birth defects.
Diagnosis and Management
The diagnosis is often made by the mother who feels that the womb is too small for the period of pregnancy. This is confirmed by ultrasound scanning and more tests may be needed to find out the cause of IUGR, if possible. The ultrasound shows that the baby’s rate of growth is smaller than usual, especially when the body measurements are taken at regular intervals, and the amount of fluid in the womb is also significantly reduced.
A baby with IUGR may die before being born, and so once diagnosed, the condition is closely monitored with regular ultrasound examination of the baby and other tests to make sure the baby is doing well. If any sign of distress is detected, it is confirmed and if appropriate, plans may be made to have a preterm delivery at a center which has facilities to take care of very small babies. Sometimes these babies cannot tolerate vaginal childbirth and a C-section will need to be done. If the delivery is very early, measures are taken to ensure that the baby’s lungs mature before birth. In spite of all possible care, babies with IUGR often do worse than others, and may have low blood sugar, low blood calcium, pneumonia, low body temperature, birth defects and infections. They need a lot of care after birth to make sure they survive the newborn period and do as well as they can.
Reviewed by Afsaneh Khetrapal Bsc (Hons)