Intrauterine growth restriction (IUGR) occurs when the baby grows at a slower pace than normally expected, and is unable to reach its full growth potential while in utero. After the 20th week of pregnancy, the measure in centimeters usually corresponds with the number of weeks of pregnancy. A lower than expected measurement may indicate the baby is not growing as it should. Other terms used for IUGR is fetal growth restriction and intrauterine growth retardation.
It’s difficult to say exactly how much a fetus weighs when it’s inside the mother. Babies with IUGR may be born small and/or undernourished. Intrauterine growth restriction, which is defined as less than 10th percentile of predicted fetal weight for gestational age, may result in significant fetal morbidity, future health problems, and mortality if not properly diagnosed.
Risks of IUGR
IUGR can put the baby at risk for complications during pregnancy, birth, and even after delivery. Some of these risks include:
- Low birth weight
- Decreased oxygen
- Low blood sugar (hypoglycemia)
- Difficulty enduring the stresses of natural vaginal birth
- High red blood cell count
- Fluctuating body temperature
- Susceptibility to infection
- Meconium aspiration. These are breathing problems caused by the newborn inhaling its first stool, which can be prematurely expelled during stressful labor, instead of after birth.
- Low Apgar scores. Apgar tests evaluate a newborn’s health and assess its need for specialized care.
Causes of IUGR
Many factors can contribute to intrauterine growth restriction, but the denominator of common cause is usually placental insufficiency.
The placenta is responsible for feeding the baby, providing it with oxygen, and eliminating its waste. If the placenta can’t do its job, the baby won’t get enough nutrients to grow to a healthy weight. Here are some common conditions that interfere with the placenta:
- Hypertension (high blood pressure)
- Heart disease
- Kidney disease
- Lung disease
- Infections such as toxoplasmosis, rubella, or syphilis
- Smoking, alcohol use, or substance abuse
Carrying multiples (twins, triplets, etc.) also increases the likelihood that at least one baby will have IUGR.
How Will My Doctor Assess for IUGR?
Since we can’t take the baby out of its mother to weigh it, we’ve developed a handful of methods to arrive at a reasonable estimate of the baby’s size. IUGR is usually detected during a routine prenatal exam in the second half of pregnancy when your practitioner measures your fundal height and finds that it’s too small for baby’s gestational age. Fundal height is measured from top of your pubic bone to the top of your uterus. She may then follow up with an ultrasound to further examine the baby’s size and check the blood flow of the umbilical artery. If either measure is abnormal, it could mean the baby isn’t receiving enough blood or nutrients from the placenta.
This is the most commonly used method for monitoring the baby’s progress. Ultrasound imaging can be used to measure the head circumference of the fetus and abdominal circumference of the mother, which can provide a basis for calculating the weight. It can also measure the volume of amniotic fluid in the uterus.
Your weight is measured and recorded at each prenatal appointment. If you are not gaining enough weight, it can be a sign that your baby isn’t gaining enough as well. A mother’s weight gain can also indicate a baby’s size. Small maternal weight gains in pregnancy may correspond with a small baby, but not always. Your physician will be able to tell you how much weight you should be putting on at each phase of your pregnancy.
A Doppler flow is a special ultrasound that uses sound waves to measure the rate of blood flow through the vessels. With the Doppler flow, your OB-GYN can estimate the amount of blood flowing through the umbilical cord and into the vessels of your baby’s brain.
This is when the doctor tests the amniotic fluid to check for infections and other abnormalities. If the root cause of IUGR is a chromosomal abnormality or birth defects, your doctor will have likely already diagnosed the condition in the first trimester with a NIPT or amniocentesis. But if the underlying cause isn’t immediately apparent, your doctor will run tests to get to the bottom of the root cause so she can better treat you and your baby. The doctor retrieves the fluid through a needle inserted through the mother’s abdomen and into the uterus.
Electronic fetal monitoring
In this test, the doctor will place small electrodes on the skin of your abdomen to measure the baby’s heart rate.
Intrauterine Growth Restriction can happen to even the healthiest of women, but there are some steps you can take to minimize the risk.
In general, take good care of your well-being in order to take good care of your baby. Eat nutritiously and strive to get at least eight hours of sleep each night. As always, avoid alcohol, tobacco, and other unhealthy substances. And last, be sure to attend all of your prenatal care appointments so that your doctor can keep an eye on your baby’s development.
The best way to prevent IUGR is to eliminate or control risk factors that may inhibit your baby’s chances of growing normally, including managing chronic conditions and pregnancy complications under the guidance of your health care provider.
Improve your diet
Research has shown that when the mother improves her nutrition, those healthful effects are passed onto her fetus.
Get plenty of rest
It is always important to get a good night’s sleep. However, in some cases, your doctor may recommend bed rest to conserve your energy for the baby’s growth. Whether at home or in the hospital, bed rest has been shown to improve circulation to the fetus, enabling it to get more oxygen and nutrients from the placenta.
Deliver the baby
In severe cases, the doctor may recommend early delivery. Your medical team may induce labor, or perform a Cesarean section depending on your individual case.