Intrauterine growth restriction, or IUGR, is when a baby in the womb (a fetus)
does not grow as expected. The baby is not as big as would be expected for the
stage of the mother's pregnancy. This timing is known as an unborn baby's "gestational
The two types of IUGR are:
symmetrical IUGR: all parts of the baby's body are similarly
small in size
asymmetrical IUGR: the baby's head and brain are the expected
size, but the rest of the baby's body is small
What Causes IUGR?
Often, IUGR happens because the fetus doesn't get enough nutrients
and nourishment. This can happen if there is a problem with:
the placenta, the tissue that brings nutrients and oxygen to the developing baby
the blood flow in the umbilical cord, which connects the baby to the placenta
Intrauterine growth restriction also can happen if a pregnant woman:
is carrying a baby that has a genetic disorder or birth
is pregnant with multiples
(such as twins or triplets)
How Is IUGR Diagnosed?
Before babies are born, doctors check their growth by measuring the mother's belly
from the top of the pubic bone to the top of the uterus. This is called the uterine
They also can do a prenatal
ultrasound, which is how IUGR often is diagnosed. A technician coats
the woman's belly with a gel and then moves a probe (wand-like instrument) over it.
High-frequency sound waves create pictures of the baby on a computer screen. These
pictures help doctors estimate the baby's size and weight. These estimates aren't
exact, but they do help health care providers track the baby's growth and see if there's
a problem. Ultrasounds also can help find other issues, such as problems with the
placenta or a low level of amniotic fluid (the fluid surrounding the fetus). Doctors
will also use ultrasounds to check the blood flow to the placenta and through the
If they think a baby has IUGR, doctors also might do such tests as:
fetal monitoring to track the baby's heart rate and movements
screening the mother for infections that could affect the baby
to look for genetic causes of IUGR (and sometimes to help them see how mature the
baby's lungs are)
How Is IUGR Treated?
Treatment for intrauterine growth restriction depends on how far along the pregnancy
is and how the baby is doing. Doctors will watch a baby with IUGR closely during prenatal visits.
They'll do ultrasounds, keep track of growth, and watch for other problems.
If the baby's mother has a condition, doctors will help her manage it. This might
include making sure she eats a healthy and nutritious diet and gains the right amount
of weight during her pregnancy. Some women might go on bed rest to try to improve
blood flow to the baby.
Sometimes, doctors will recommend inducing
labor and delivery early. They might do this if the baby seems to have stopped
growing, or if there's a problem with the placenta or the blood flow in the umbilical
Babies with IUGR are more at risk for some kinds of health problems. Those born
early or who are very small at birth are more likely to need to stay in the hospital
for a longer time. They also might need special care in the neonatal
intensive care unit (the NICU).
Other problems that can be related to intrauterine growth restriction include:
problems with breathing and feeding
trouble keeping a steady body temperature
abnormal blood cell counts
low blood sugar level (hypoglycemia)
problems fighting off infections
The long-term effects of IUGR on a baby may depend on the condition that caused
What Can I Do if My Baby Has IUGR?
If your baby might have IUGR, follow your doctor's advice and go to all prenatal
visits and testing appointments.
This helps your doctor see how your baby is developing and growing.