Intra Uterine Growth Restriction (IUGR)

INTRAUTERINE GROWTH RESTRICTION (IUGR)

INTRODUCTION

Intrauterine growth restriction (IUGR) is a term used to describe a condition in which the fetus is smaller than expected for the number of weeks of pregnancy. Another term for IUGR is fetal growth restriction. Newborn babies with IUGR are often described as small for gestational age (SGA).

A fetus with IUGR often has an estimated fetal weight less than the 10th percentile. This means that the fetus weighs less than 90 percent of all other fetuses of the same gestational age. A fetus with IUGR also may be born at term (after 37 weeks of pregnancy) or prematurely (before 37 weeks).

Newborn babies with IUGR often appear thin, pale, and have loose, dry skin. The umbilical cord is often thin and dull-looking rather than shiny and fat. Babies with IUGR sometimes have a wide-eyed look. Some babies do not have this malnourished appearance but are small all-over.

CAUSES OF IUGR

Intrauterine growth restriction results when a problem or abnormality prevents cells and tissues from growing or causes cells to decrease in size. This may occur when the fetus does not receive the necessary nutrients and oxygen needed for growth and development of organs and tissues, or because of infection. Although some babies are small because of genetics most IUGR is due to other causes. Some factors that may contribute to IUGR include the following:

Maternal factors:

 

§  high blood pressure
§  chronic kidney disease
§  advanced diabetes
§  heart or respiratory disease
§  malnutrition, anemia
§  infection
§  substance abuse (alcohol, drugs)
§  cigarette smoking

Utero placental factors :

§  decreased blood flow in the uterus and placenta
§  placental abruption (placenta detaches from the uterus)
§  placenta previa (placenta attaches low in the uterus)
§  infection in the tissues around the fetus

Fetal factors:

§  multiple gestation (twins, triplets, etc.)
§  infection
§  birth defects
§  chromosomal abnormality

COMPLICATIONS OF IUGR

IUGR can begin at any time in pregnancy. Early-onset IUGR is often due to chromosomal abnormalities, maternal disease, or severe problems with the placenta. Late-onset growth restriction (after 32 weeks) is usually related to other problems.

With IUGR, the growth of the baby's overall body and organs are limited, and tissue and organ cells may not grow as large or as numerous. When there is not enough blood flow through the placenta, the fetus may only receive low amounts of oxygen. This can cause the fetal heart rate to decrease placing the baby at great risk.

Babies with IUGR may have problems at birth including:

§  decreased oxygen levels

§  low Apgar scores
§  meconium aspiration (inhalation of the first stools passed in utero), which can lead to difficulty breathing
§  hypoglycemia
§  difficulty maintaining normal body temperature
§  polycythemia (increased red blood cells)

Severe IUGR may result in stillbirth. It may also lead to long-term growth problems in babies and children.

Intrapartum Asphyxia

Because the fetus is compromised with IUGR, its ability to tolerate the stress of labor is decreased. Therefore, when uterine contractions occur and the flow of blood to the fetus is diminished with each contraction, the fetus with IUGR may not be able to adapt. This leads to an imbalance between the ability of the placenta to supply the fetus with oxygen and nutrients and the need for these substances. When an imbalance occurs, this may lead to an accumulation of byproducts resulting in acidosis which can be harmful. If intrapartum asphyxia is allowed to progress, irreversible brain damage can occur.

Neonatal Hypoglycemia and Hypocalcemia

As the result of IUGR, a newborn may be deficient in glucose (sugar) and calcium. The lack of these important substances can result in significant compromise to the newborn and result in neurological damage.

Meconium Aspiration

This occurs when the fetus defecates in the uterus resulting in the appearance of a brown, murky substance. Meconium aspiration is of major concern. In severe forms, the newborn may develop lung disease resulting in respiratory and cardiovascular complications that could lead to neonatal death.

Neurodevelopmental Delay

A number of studies have shown that fetuses with significant IUGR are at higher risk for developmental delays, cardiovascular disease, and other problems later in life. For these reasons, and those stated above, it is important to identify the fetus with IUGR and manage the pregnancy accordingly

DIAGNOSIS OF IUGR

§  Fundal Height

The height of the fundus can be measured from the pubic bone. This measurement in centimeters usually corresponds with the number of weeks of pregnancy after the 20th week. If the measurement is low for the number of weeks, the baby may be smaller than expected.

§  Ultrasound
Ultrasound is a more accurate method of estimating fetal size. Measurements include the diameter of the head (Biparietal Diameter or BPD), the circumference of the head, the circumference of the abdomen, and the length of the femur bone of the leg. The fetal abdominal circumference is a helpful indicator of fetal nutrition.

§  Doppler flow

Another way to interpret and diagnose IUGR during pregnancy is Doppler flow, which use sound waves to measure blood flow. The sound of moving blood produces wave-forms that reflect the speed and amount of the blood as it moves through a blood vessel. Blood vessels in the fetal brain and the umbilical cord blood flow can be checked with Doppler flow studies.

§  Mother's weight gain

A mother's weight gain can also indicate a baby's size. Small maternal weight gains in pregnancy may correspond with a small baby.

MANAGEMENT OF IUGR

Management of IUGR depends on the severity of growth restriction, and how early the problem began in the pregnancy. Generally, the earlier and more severe the growth restriction, the greater the risks to the fetus. Careful monitoring of a fetus with IUGR and ongoing testing may be needed.

Some of the ways to watch for potential problems include the following:

§  Fetal movement counting - keeping track of fetal kicks and movements. A change in the number or frequency may mean the fetus is under stress.

§  Non Stress Testing - a test that watches the fetal heart rate for increases with fetal movements, a sign of fetal well-being.

§  Biophysical profile - a test that combines the non stress test with an ultrasound to evaluate fetal well-being.

§  Ultrasound - Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels. Ultrasounds are used to follow fetal growth.

§  Doppler flow studies - a type of ultrasound which use sound waves to measure blood flow.

 

TREATMENT OF IUGR

Although it is not possible to reverse IUGR, some treatments may help slow or minimize the effects. Management will be determined based on:

§  Maternal and fetal overall health, and medical history

§  the extent of the condition
§  tolerance for specific medications, procedures

Nutrition
Some studies have shown that increasing maternal nutrition may increase gestational weight gain and fetal growth.

Bedrest
Bedrest in the hospital or at home may help improve circulation to the fetus.

Delivery
If IUGR endangers the health of the fetus, then an early delivery may be necessary.

 

PREVENTION

Intrauterine growth restriction may occur, even when the mother is in good health. However, some factors may increase the risks of IUGR, such as cigarette smoking and poor maternal nutrition. Avoiding harmful lifestyles, eating a healthy diet, and getting prenatal care may help decrease the risks for IUGR. Early detection may also help with IUGR treatment and outcome.