Fetal Growth Restriction: Reasons, Diagnosis And Risks Involved

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Fetal growth restriction (FGR) is a condition in which the baby does not develop to its optimum growth and weight during pregnancy.

The common reasons for this condition include high blood pressure of the mother, multiple pregnancies, infections, and consumption of alcohol or smoking during pregnancy. Therefore, it is important to regularly monitor the growth and development of the baby during this period to avoid any complications.

Read on to know about FGR, its causes, symptoms, treatment, and preventive measures.

What Is Fetal Growth Restriction?

Intrauterine growthⁱDevelopment of the fetus within the uterus restriction (IUGR), is a condition which is applied for neonates born with clinical signs of retarded or abnormal fetal development and fetal malnutrition. In this condition, the size of the baby is smaller than the average size at that age.

Different types of IUGRs during pregnancy

There are two main types of intrauterine growth restrictions occurring during pregnancy:

1. Symmetrical or primary IUGR: The baby has a symmetrical body in proportion with the internal organs, but is smaller than the size of a normal baby of that age.

2. Asymmetrical or secondary IUGR: The baby has a normal head and brain, but the body is small for gestational age. This condition is not evident until the third trimester.

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The third variety of IUGR is seen in developing countries and is termed mixed IUGR. These neonatesⁱA newborn child less than four weeks old have fewer and smaller-sized cells and exhibit symptoms of both symmetrical and asymmetrical IUGR at birth (15).

Reasons For Restricted Growth Of Fetus During Pregnancy

The causes of IUGR are segregated into three broad categories: maternal, fetal and placentalⁱIt is a temporary vascular organ that grows during pregnancy and provides the growing fetus with oxygen and nutrition (1).

• Maternal health is important for the baby to get all the essential nutrients for its growth.

• Fetal health is necessary to make sure the baby receives the nutrients supplied by the mother.
• The placenta should be healthy enough to carry the nutrients from the mother to the fetus.

All the factors mentioned below fall into one of the three categories:

1. Pregnancy-induced hypertension: During pregnancy, your blood pressure is constantly monitored to check for hypertension. An increased blood pressure may indicate hypertensive disorder of pregnancy (gestational hypertension, chronic hypertension preeclampsia). The reduced placental blood flow cuts down on the supply of sufficient oxygen and supplements to the fetus, thereby leading to fetal hypoxemia and fetal growth retardation, known as placental dysfunction (2). It may also cause preterm birth and fetal distress. Fetal Anemia can also be the reason for fetal distress.

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2. Multiple pregnancies: In some cases of multiple pregnancies, the slow fetal development is because of the placental insufficiency to meet the nutritional demands of multiple babies. Moreover, the chances of hypertensive disorder are also high in multiple pregnancies. IUGR occurs in 25-30% of twin pregnancies (3).

3. Infections: Any infections transferred from the mother during pregnancy can lead to slow fetal growth. Infections such as syphilis (a sexually transmitted bacterial infection), toxoplasmosis (a parasitic infection transmitted mainly through under-cooked meat), cytomegalovirus (viral infection with significant impact during pregnancy due to weaker immunity), and rubella (German measles) increase the chances of IUGR (4).

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4. Lower level of amniotic fluids: It is necessary to have sufficient amniotic fluid in the sac for normal fetal development to happen. However, low fluid level (also termed as oligohydramnios) can lead to fetal growth restriction (5). Various factors, including the health of the mother, certain medications, and a slight rupture of the amniotic sac cause the fluid levels to deplete.

5. Placental insufficiency: In this condition, the placenta does not work properly. This leads to insufficient oxygen supply and inadequate fetal nutrition from the mother, resulting in slow growth (6).

6. Abnormalities of the umbilical cord: The cord connects the fetus with the placenta. It contains one umbilical vein and two umbilical arteries, which carry blood between the fetus and the placenta. However, if there is only one artery in the umbilical cord, then this abnormality leads to fetal growth restriction (7).

7. Other maternal and fetal reasons include:

• Small size of the mother, leading to constitutionally small baby

• The mother’s nutritional intake during pregnancy

• Abnormal shape or size of the womb

• Chronic illness in the mother such as sickle cell disease, diabetes, hypertension, heart disease

• Chromosomal abnormalities

• Genetic and skeletal abnormalities in the fetus.

Be watchful

Clotting disorders, kidney diseases, thyroid diseases, and anemia during pregnancy may also cause IUGR (16).

• smokes

• is underweight (maternal undernutrition)

• drinks alcohol

• takes drugs

• follows poor diet

• is exposed to high doses of radiation or chemicals (8)

Quick fact

Not getting enough oxygen and nutrition from the mother’s placenta because of being at higher altitudes may result in IUGR (16).

Your baby’s size will be monitored throughout the pregnancy, and the measurements will be put on a growth chart. If the doctor finds any abnormality, she does an ultrasound scan to measure the baby’s growth accurately.

Fetal growth measurement is important because slow growth could lead to certain health problems in the baby.

Risks of IUGR

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Babies with IUGR have increased chances of getting health issues both before and after birth. The risks include (9) (10):

• Reduced fetal weight or Low birth weight

• Problems with breathing and feeding

• Decreased ability to fight infection

• Fetal Hypoglycemia (low blood sugar level)

• Fetal hypoxia

• Fetal Asphyxia

• Intrauterine hypoxia

• Low Apgar Scores (Apgar score is a test carried out to evaluate the physical condition of the newborn and to determine any immediate need of medical care. The score is determined on a scale of 0 to 2, with 2 being the best)

• Abnormally high red blood cell count

• Neurological problems

• Trouble in maintaining the body temperature

• Stillbirth

In order to avoid these risks in the baby, the doctor measures the fetal growth regularly when you go for health check-ups.‘

How Is Fetal Growth Restriction Diagnosed?

The fetal size can be estimated by measuring the fundal height. However, there are other procedures to diagnose IUGR and assess the baby’s health:

1. Ultrasound: An ultrasound uses sound waves to create images of the baby’s structure and measure its head and abdomen. These measurements are compared with the growth chart to estimate the fetal weight.

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3. Doppler flow: The technique is used to measure the speed and amount of blood flow into the blood vessels of the fetal brain and the umbilical cord, using sound waves.
4. Weight checks: It is another way of estimating the fetal growth. During every prenatal visit, the doctor will check and record the mother’s weight. If the expecting woman is not gaining appropriate weight, it could result in the fetus’ slow growth. Slow fetal growth can be effectively managed in expecting mothers through regular checkups and a healthy lifestyle.

A mom-blogger shared her journey of carrying a baby with intrauterine growth retardation in her blog, ‘Lanonativa.’ She recounts, “My baby had an intrauterine growth retardation. He was always a lot below the average, but the doctor was great and he used to say: you are going to have a Ferrari, small but powerful. As I had a very difficult pregnancy and it was very important to check the fetal growth, every two weeks the obstetrician measured abdominal circumference, head circumference, femur, biparietal diameter, and occipital frontal diameter.

“I think that normally if everything is going fine, the visits to the doctors are just once a month or even less, but as I haven’t had any other pregnancy I am not sure if every time you go, they measure all these things, I don’t think so (i).”

How is IUGR managed?

IUGR is managed based on its severity. It depends on the gestational age at which it is diagnosed. IUGR can be divided into early onset IUGR and late onset IUGR, depending on whether its occurring prior to 34 weeks or after that. According to the fetal compromise, IUGR is divided into stages I-IV based on the effective fetal weight, cerebroplacental ratioⁱAn ultrasound tool used to predict an adverse pregnancy outcome , uterine artery PIⁱA technique to evaluate fetal well-being by calculating the pulsation in the uterine artery , flows in ductous venosus and management based upon the stage and gestational age at diagnosed management can be planned. 

• Stage 0: You are treated as an outpatient with a Doppler test done every two weeks. If the results are consistent, your delivery can be at term. But if the Doppler results are abnormal, the fetus moves to Stage I.

• No IUGR: Where the baby is constitutionally small but the doppler parameters are normal, pregnancy can be taken until 40 weeks. Labor may be induced at 40 weeks if the patient does not go into labor by 40 weeks and there are no contraindications for normal vaginal delivery. If the gestational age is less than 40 weeks, the mother is monitored weekly until 40 weeks and induction is done earlier in the case of any deterioration.

• Stage I: Weekly monitoring is required until 37 weeks and induction for labor is done if no contraindications for normal vaginal delivery. 
• Stage II: Stricter monitoring is needed every two to three days. Delivery is done by cesarean section (CS) as the baby is unable to withstand the stress of labor. This is usually advised at 34 weeks.
• Stage III: Monitoring every 24-48 hours and mode of delivery is usually via CS usually at 30 weeks after steroid cover.
• Stage IV: Monitoring every 12-24 hours and delivery via CS at gestational age more than 26 weeks. Long-term prognosis remains poor due to extreme prematurity.

If your doctor suspects IUGR, then:

• You will have regular scans to check your baby’s growth. With a Doppler test, the amount of blood flow from the placenta to the fetus is checked.

• If there is any concern about the fetal growth, your doctor will recommend CTG monitoring, regular scans, and consultant appointments.

• You will be advised to monitor the movements of your baby closely.

• If growth restriction is severe, then the doctor may recommend an early delivery by C-section as vaginal delivery would be stressful (11). In such a case, your baby will be put in the neonatal care unit, where it can grow better than inside your womb.

Above all, you need to take care of yourself by eating nutritious food and taking ample rest.

What should you do in the case of IUGR?

Visit your doctor regularly and get carefully checked. Closely monitor your baby’s movement patterns. If your baby does not move very often, contact your doctor and follow their instructions.

Ask your doctor several questions such as,

• What activities should you avoid?

• What precautions should you take?

• What symptoms or problems should you watch out for?

There is little you can do to control IUGR, but certain lifestyle changes could be of help.

How to prevent IUGR?

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The below measures can reduce the risk of IUGR:

• Eat a healthy diet. Healthy foods provide proper nourishment to your baby.

• Quit smoking and drinking alcohol during pregnancy.

• Limit the intake of caffeine.

• Check with your doctor if any medications that you are taking pose a risk of IUGR.

• Get plenty of rest and keep stress at bay. Try to get at least eight hours of sleep every day.

• Stay fit by exercising.

Infographic: How To Prevent Intrauterine Growth Restriction?

Fetal growth restriction is when a baby is not growing properly in the womb. Following simple yet critical measures highlighted in this infographic is essential to prevent this phenomenon. Also, attend regular prenatal checkups and follow your doctor’s advice for a healthy pregnancy and baby.

Illustration: Momjunction Design Team

Fetal Growth Restriction is a serious condition that can affect a baby’s growth. Learn about its different types, various reasons that cause this condition, TORCH infections, diagnosis, and treatment of FGR.

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Reviewer Author Editor Fact Checker

Dr. Asmita KaundalMD

Dr. Kaundal has 10 years of experience as an obstetrician and gynecologist and is currently working as a consultant IVF at Matritava Advanced IVF and Training Centre, New Delhi.She has previously worked at Lady Hardinge Medical College, MKW and IMB IVF centre, Apollo Cradle Royale and AIIMS, New Delhi.

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shreeja pillaiMSc

Shreeja holds a postgraduate degree in Chemistry and diploma in Drug Regulatory Affairs from the University of Mumbai. Before joining MomJunction, she worked as a research analyst with a leading multinational pharmaceutical company.

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Swati PatwalM.Sc. (Food & Nutrition), MBA

Swati Patwal is a clinical nutritionist, a Certified Diabetes Educator (CDE) and a toddler mom with more than a decade of experience in diverse fields of nutrition. She started her career as a CSR project coordinator for a healthy eating and active lifestyle project catering to school children.

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Lorraine TeronMSc

Lorraine is a postgraduate in Life Science from Mount Carmel College and previously worked as a freelance scientific illustrator. As a project associate and lab technician at the Centre for Cellular and Molecular Biology, Lorraine received valuable insights into Covid-19, transgenerational epigenetic inheritance, and neuro-degenerative diseases.

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