Intrauterine Growth Restriction
Low Birth Weight Babies

Low Birth Weight IGR Pictures

Fetus Growth Restriction

Low Birth Weight Baby (Left)

No obvious signs for expectant moms to look out for.

Not smoking or drinking during pregnancy can help prevent IUGR.

Very Small Babies


What Is Intrauterine Growth Restriction?
What Are The Symptoms?
How Is It Diagnosed?
How Is It Treated?
What Causes It?
What Are The Risks To Babies Born With IUGR?
Can It Be Prevented?
Will It Occur In Every Pregnancy?
Do All Low Birth Weight Babies Have IUGR?

What Is The Difference Between SGA and IUGR?
Difference Between A Baby Born Premature and Those With IUGR?
Why Is It Important To Diagnose IUGR After Delivery?
When Do We Need To Consult A Pediatric Endocrinologist?

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Common Pregnancy Problems

Other Names: Intrauterine growth restriction (IUGR) is also known as Intrauterine growth retardation (image), fetus growth restriction and small-for gestational age (SGA).

What Is Intrauterine Growth Restriction?

It is a medical term used to describe a baby during pregnancy that is smaller than normal. A diagnosis is given where the baby's weight is below the 10th percentile for its gestational age. In other words it weighs less than 90 percent of other babies the same age growing in their mother's womb. It is a relatively common condition which occurs in about 3 percent of all pregnancies. It is the second leading cause of perinatal death (meaning death after 24 weeks of gestation or those that die within days of childbirth). Intrauterine growth restriction (IUGR) can occur when the placenta or its blood supply is not acting as it should, so the fetus receives less nutrients and oxygen than it needs. This can, outside of being fatal, cause several other problems for the baby including:

• Difficulties handling the stress of a vaginal delivery.
• Low blood sugar levels and less resistance to infection at birth.
• Abnormally high red blood cell count and difficulties maintaining a stable body temperature.

Given the risks involved, early diagnosis, evaluation and management is critical because it can improve the outcome for the baby.

What Are The Symptoms?

There are rarely any outward signs that a baby has IUGR. A mother may instinctively feel that her baby bump is not as large as it should be, but this is not always an indication.

How Is It Diagnosed?

Prenatal Visits
IUGR is usually first noted in a routine prenatal visit when the doctor or nurse measures the fundal height. That is, the distance between the public bone and the uterus. A lag of 4cm or more suggests IUGR.

Accurate Due Date
Accurate estimating of the pregnancy due date is essential for the diagnosis of IUGR. This generally means estimating from the date of the last period in a woman with a regular menstruation cycle. Or it can be carried out with a prenatal ultrasound scan performed no later than week 20 of pregnancy when the margin of error is between 7-10 days. Ideally an ultrasound will be carried out between weeks 8-13 to measure gestational age. Although an ultrasound is routinely carried out in the third trimester of pregnancy to estimate the fetus' weight - a common mistake technicians make is to change the mother's due date based on this information. Changing the due date based on a third trimester ultrasonogram can result in failure to recognize IUGR.

Ultrasound Biometry
A fetal ultrasound biometry, commonly called an A-scan, is the gold standard for assessing the growth of a fetus. It will be used to measure the head and abdominal circumference. It will also measure biparietal diameter, that is the distance between the parietal bone and the distal bones in the skull. If performed up to week 20, it has an error potential of about one week in estimating the fetus' age. This rises to 2 weeks between weeks 20 to 36 and 3 weeks after that. This is why optimally it is carried out between weeks 8 to 13.

How Is It Treated?

One of the best predictors of a baby's health is its birth weight. The more normal and healthy the birth weight, the fewer the complications they are likely to experience. That is why it is important to diagnose IUGR as soon as possible because doctors can then try to boost the growth rate in the womb before birth. As no effective treatments for IUGR are known, the goal is to deliver the most mature fetus as possible, in the best physiological condition while at the same time minimizing the risk to the mother. If you have been diagnosed with IUGR a variety of approaches may be taken, depending in the cause. These include:

Medications to correct blood flow to the placenta or to correct a medical issue which is preventing good blood flow (for example, if the umbilical cord is wrapped around the fetus causing compression).

Bed rest until the baby is born with weekly nonstress tests (NST) to monitor the fetus size. Levels of amniotic fluid may also be measured.

Intravenous feedings of the baby if necessary. If labor needs to be induced, and the baby is less than 36 weeks old (premature labor), steroids are usually administered to boost the fetus' lungs growth in order to significantly reduce the risks of respiratory distress syndrome.

If the environment in the uterine is poor, and the fetus' lungs have matured enough, labor induction by Cesarean section delivery may be the best option. In such instances the mother and child can still have a normal hospital stay and C-section recovery advice still applies. Extended stays are only necessary where the baby is born very prematurely or if there are complications after birth.

What Causes It?

Why the fetus should not receive enough nutrients or oxygen through the placenta can have many causes. These include:

Placenta previa.
Placenta insufficiency caused by postmaturity (overdue).
• Low levels of amniotic fluid or oligohydramnios.
• Severe anemia in pregnancy.
• Thrombophilia (tendency for thrombosis/blood clots).
• Carrying multiples (twins, triplets) is also a factor, although this is more likely to be due to overcrowding rather than anything specifically wrong with the placenta. In the case of twins, one may have better access than the other to blood supplies.
• Chromosomal abnormalities and genetic disorders are also associated with IUGR such as Down's syndrome, Edwards syndrome, Turner's syndrome and Patau's syndrome.
• Infections during pregnancy such as toxoplasmosis, rubella and syphilis can also affect the weight of the baby.
• Prolonged high-altitude exposure in the mother.
• Abnormal size or shape of the mother's womb.
• Blood supply can be limited if the umbilical cord around part of the fetus' body.

Risk Factors Which May Contribute

If the mother:

• Does not eat a good nutritious diet.
• Abuses alcohol.
• Uses illegal drugs or smokes.
Heart disease in pregnancy can also be a factor.
• Women who have chronic conditions such as kidney disease or diabetes are more prone.

• Suffers chronic hypertension or develops pregnancy associated high blood pressure. For more see, hypertension during pregnancy.

What Are The Risks To Babies Born With IUGR?

• Hypoxia - lack of oxygen
Hypoglycemia - or low blood sugar.
• Polycythemia - increased amounts of red blood cells.
• Hyperviscosity - reduced blood flow due to excess red blood cells.

• Meconium Aspiration -when the baby swallows part of the first bowel movement which can lead to bacterial pneumonia.

Increasingly, data supports the idea that the complications of IUGR can last well into adulthood. Several studies have noted that people who suffered IUGR in the womb have a greater risk of developing metabolic syndrome later in life. This can manifest as obesity, hypercholesterolemia, hypertension, coronary heart disease and type 2 diabetes. Additionally mental health problems appear to be more common in children with growth restriction.

Can It Be Prevented?

By reducing some of the risk factors such as smoking and drinking, and ensuring she eats a healthy diet, a woman can reduce her chances of IUGR. Good prenatal care and gaining pregnancy weight at the recommended rate can also help. When preparing for pregnancy, ensure any chronic conditions such as diabetes or hypertension are under control before conception. There are some conflicting studies to the benefits of taking aspirin during pregnancy by women at high risk of IUGR. One study reported a decline in the rate of IUGR from 61 percent to 13 percent in those treated with aspirin and dipyridamole.

: How much weight should I gain during pregnancy?

Will It Occur In Every Pregnancy?

No, IUGR in one pregnancy does not increase the risk in subsequent pregnancies. It is more frequent in first pregnancies, 5th pregnancies and all subsequent ones after that. It is also slightly more common in women under 17 and those experiencing a pregnancy after 35.

Do All Low Birth Weight Babies Have IUGR?

No, sometimes babies are simply born smaller than average (small-for gestational age). This can be genetic, where either or both parents have small body frames - and not caused because their growth was restricted in the uterus. In fact, only about one third of all low weight babies have IUGR.

What Is The Difference Between SGA and IUGR?

The average time of growth in the womb is 40 weeks, and the average full-term baby weighs 7.5 pounds. This is know as appropriate for gestational age (AGA). Although a premature baby may be smaller, it will still be AGA because its weight is appropriate for the time it spent in the womb. A SGA infant on the other hand is below the 10th percent average for its age. Although IUGR and SGA are often used interchangeably, there is a difference. The term IUGR should not be used where there is no evidence that abnormal genetical or environmental influences caused a baby to be smaller for its age. In reality, IUGR only accounts for the 3rd percentile (the baby weighs less than 97 percent of other babies the same age), and not the 1 in 10 or 90 percent of AGA newborns. So, although all IUGR babies are SGA, not all SGA infants are IUGR.

How Can Doctors Tell The Difference Between A Baby Born Premature and Those With IUGR?

After delivery and childbirth the doctor will carry out a physical examination, checking skin thickness and texture, looking at the soles of the feet, the firmness of ears and the appearance of genitals. Neurological responses will also be checked, such as flexion of feet and hands. This will determine the presence or not of IUGR.

Why Is It Important To Diagnose IUGR After Delivery?

Doctors need to determine if a small newborn is premature or IUGR because the medical difficulties they face can be different. Some premature babies have no problems at all, while others may be vulnerable to respiratory distress syndrome, jaundice and sleep apnea. On the other hand, newborns with IUGR are prone to hypoglycemia (low blood sugar), hypocalcemia (low blood calcium), polycythemia (blood disorder) and meconium aspiration (causes lung problems which may require a ventilator).

When Do We Need To Consult A Pediatric Endocrinologist?

A pediatric endocrinologist specializes in growth disorders. They are normally only consulted if an IUGR infant does not catch up to the normal height range for its height within the first 12 months of birth. When the child is older, the specialist may recommend specific medical treatments to enhance the child's growth.

Other Pregnancy Complications

Bleeding during Pregnancy
HELLP Syndrome
Ovarian tumors in pregnancy.
Placental Abruption

  Related Articles on Intrauterine Growth Restriction

For more guidance for pregnant women, see the following:

How much weight gain is normal in pregnancy?
Digestive problems in pregnancy: Heartburn, peptic ulcers and more.

Return to Homepage: Womens Health Advice

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