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Everything About Intrauterine Growth Restriction (IUGR)

Everything about Intrauterine Growth Restriction (IUGR)

Table of Contents

Intrauterine growth restriction (IUGR) is when a baby in the womb has not grown as expected. Under these conditions, the fetus grows very slowly in the mother’s womb, and as a result, the fetus weighs much less than its normal weight during the week of pregnancy. This slow fetus growth is usually detected in the uterus with ultrasound measurements. There are many reasons for this limitation in pregnancy growth.

What is intrauterine growth restriction (IUGR)?

Intrauterine growth restriction, also known as fetal growth restriction or FGR, is a condition in which a baby is born smaller than expected in relation to the gestational age or the number of weeks the baby is in the womb. These babies typically weigh less than the tenth percentile. This means that they weigh less than 90% of unborn babies at the same gestational age. These babies are small in proportion to all parts of their body or asymmetrically small, meaning their body parts are smaller.

Babies with IUGR are more likely to have various health problems before, during, and after birth. However, not all babies who weigh in the 10th percentile have IUGR complications or concerns.

Why is the baby’s size important?

The best predictor of a baby’s health is its birth weight. Low birth weight babies may have problems near birth. Because of the risk of some of these problems, such as fighting infections or maintaining normal body temperature, doctors will perform tests to see if the baby is growing well before or after birth.


Some babies are born smaller than normal. However, only about one in the third of these babies have IUGR. Babies who have IUGR are more likely to have certain health problems, including:

  • A difficult time handling the stress of vaginal delivery
  • Increased risk of being stillborn
  • Low blood sugar level at birth
  • Trouble maintaining body temperature
  • An abnormally high red blood cell count
  • Lower resistance to infection



Limited growth associated with IUGR is due to the baby not receiving enough nutrients and oxygen in the womb for normal growth. Many factors can lead to an insufficient flow of nutrients and oxygen. Possible factors fall into three main categories: some related to the baby, some to the mother, and others to abnormalities in the placenta or uterus.

Maternal related factors

The baby may be underweight due to problems in the mother. These problems include:

  • A chronic condition that affects the mother’s heart, kidneys, lungs, liver, or blood, such as high blood pressure, severe diabetes, or autoimmune disease
  • Smoking or abuse of other substances
  • Taking certain medications such as anticonvulsants
  • Having infections that may be transmitted to the baby, such as cytomegalovirus or rubella
  • Poor nutrition
  • Weight gain or deficient weight

Baby related factors

Weight loss may be due to fetal problems; these include:

  • Birth defects
  • Chromosome or genetic abnormalities
  • Infections
  • Being part of multiple births, such as twins or triplets

Placenta and uterine-related factors

Sometimes weight loss is due to placental and uterine problems that include:

  • Small placental size
  • Abnormal blood flow through the placenta
  • Placental masses
  • Large uterine fibroids behind the placenta
  • An abnormal insertion of the umbilical cord into the placenta
  • Placental abruption
  • An abnormally shaped uterus



Doctors have many methods for estimating the size of babies during pregnancy. One of the easiest is to measure the distance from the mother fundus to the pubic bone. After the 20th week of pregnancy, the measurement in centimeters usually corresponds to the number of pregnancy weeks.

Measuring less than expected may indicate that the baby is not growing as well as it should. There are other diagnostic methods. Arjang Naim MD uses advanced devices to accurately ultrasound the developing fetus to ensure normal fetal growth.


Ultrasound is the main method of examining fetal growth in the womb. In this method, an image of the fetus is taken using sound waves, and the doctor can see the fetus in the womb. Ultrasound can be used to obtain fetal head and abdomen sizes. By comparing these measurements with the growth chart, fetal weight can be estimated. Ultrasound can also be used to measure amniotic fluid. Lack of amniotic fluid can indicate fetal growth restriction in the uterus.

Doppler ultrasound uses sound waves to measure the amount and speed of blood flow in the arteries. The doctor uses this method to check the blood flow in the umbilical cord and the fetal brain.

Weight checks

The doctor measures and records the mother’s weight at each routine pregnancy examination. Maternal weight gain can indicate fetal growth rate, and if the maternal weight does not increase, it can indicate fetal growth problems.

Fetal monitoring

In this method, by placing sensitive electrodes on the mother’s abdomen attached to a screen, the fetal heart rate and pattern are measured and displayed on a screen.


In an amniocentesis test, a small amount of amniotic fluid is removed by inserting a needle into the mother’s abdomen and uterus. This test can detect infections or chromosomal abnormalities that lead to fetal growth restriction.


Intrauterine Growth Restriction may occur even when the mother is perfectly healthy, but there is a way to reduce its risk. These include:

  • See your obstetrician regularly. Diagnosing potential problems early helps with timely treatment.
  • Pay attention to your baby’s movements. A baby who does not move regularly or stops moving may have a problem. Contact your doctor if you notice any changes in your baby’s movement.
  • Check your medications. Sometimes a mother’s medication for other health problems can lead to problems in the unborn baby. Therefore, be sure to inform your obstetrician about all your medications.
  • Eat healthy food. Healthy foods and adequate calorie intake help to nourish the baby, thus reducing the chances of having an Intrauterine Growth Restriction baby.
  • Get enough rest during pregnancy. Adequate rest will help you feel better and may help your baby grow. Try to get eight hours of sleep a night. An hour or two of rest in the afternoon is also helpful.
  • Practice healthy lifestyle habits. If you drink alcohol, take drugs, or smoke, stop taking them.

Living with intrauterine growth restriction

If your baby has IUGR, you may need to give birth early. But the timing of the delivery depends on the condition of your baby. Sometimes, babies with IUGR need to grow in the womb. If the baby is constantly overweight in the womb, there is no need for preterm birth. But if your baby is not growing in the womb or has other problems, your doctor may decide that preterm delivery may help. In this case, the doctor decides to give birth earlier.

If there are no signs of baby problems during delivery, a normal delivery can be done, but some babies with IUGR are weak, so a cesarean section may be safer. A baby with IUGR should stay in the hospital longer than usual after birth. This is especially true for babies who are born prematurely. They need natural breathing and nutrition before going home. Also, they usually have to weigh 5 pounds before leaving the hospital. These babies will probably reach normal height and weight by about two years of age.

The bottom line

Your doctor will perform tests during pregnancy to ensure the fetus grows normally. An ultrasound of the uterus is the most important test to ensure fetal growth. Ultrasound assesses the position of the fetus in the uterus. During the ultrasound, the size of the fetus’s head, abdomen, and legs are examined. These measurements show whether the fetus has grown normally. Most of the factors that limit intrauterine growth are beyond our control, so the mother or fetus has no role in causing intrauterine growth restriction.

However, factors such as smoking, alcohol consumption, or the misuse of certain illicit drugs can limit intrauterine growth. If the fetus experiences intrauterine growth restriction during pregnancy, this complication will not necessarily recur in the next pregnancy. Always remember to follow your prenatal visits regularly during pregnancy. You should check fetal movement daily. If the number of fetal movements decreases, a problem such as diseases may exist. Eating healthy foods and good calories during pregnancy helps prevent intrauterine growth restriction.

Arjang Naim, MD, and his team provide complete pregnancy care to ensure the health of the mother and baby, and if an IUGR baby is born, they provide the necessary care.

Additional questions

  1. What genetic disorders cause IUGR?

Single-gene disorders, such as Cornelia de Lange syndrome, Fanconi’s anemia, Russell Silver syndrome, Bloom syndrome, and some skeletal dysplasia, have been associated with IUGR.

  1. What foods increase fetal growth?

Protein is very important for baby growth during pregnancy. Good protein resources include:

  • Lean meat
  • Poultry
  • Seafood
  • Eggs
  • Beans and peas
  • Nuts
  • Seeds
  • Soy products
  1. What drugs are given for convulsions in pregnancy?

Proper seizure control should be performed in the third trimester of pregnancy to prevent seizures during childbirth. Benzodiazepines or phenytoin are effective in discontinuation of seizures during childbirth. Phytomenadione should be prescribed immediately after birth.

  1. What are the types of the abnormal uterus?
  • Uterus didelphys (double uterus)
  • Arcuate uterus (uterus with a dent on the top part)
  • Unicornuate uterus (one-sided uterus)
  • Bicornuate uterus (heart-shaped uterus)
  • Bicornuate uterus (heart-shaped uterus)
  1. Does IUGR mean high risk?

A doctor may diagnose a high-risk pregnancy depending on the cause of growth restriction. However, most fetuses diagnosed with IUGR are healthy and need more monitoring during pregnancy.