What Is Intrauterine Growth Restriction

Overview

Intrauterine growth restriction (IUGR) is a disorder where a foetus does not reach its maximum development potential while the mother is pregnant. It is linked to poor newborn outcomes and long-term health effects. At gestational age, a baby who is below the 10th percentile for weight or length during pregnancy or postpartum is considered tiny. A pregnancy underweight infant and a pregnancy malnutrition infant are two separate conditions. Regardless of whether an infant has these issues, the situation may affect them.¹

It is often diagnosed at the prenatal stage, though it can also be detected at the newborn stage, based on a clinical examination, clinical assessment of nutritional status (CAN) score, and anthropometry index. The health of pregnant women is at risk due to IUGR; it’s estimated to affect 10-15% of them.

IUGR is divided into two categories:

Primary or symmetric IUGR

All internal organs are smaller in this situation. 20% to 30% of patients with IUGR have this condition. Early gestational intrauterine infections (TORCH), Maternal alcohol use, and genetic or chromosomal reasons are the causes of symmetric or primary IUGR.

Asymmetric or secondary IUGR

In this situation, the abdomen is smaller than the head and brain, which are both normal sizes. The third trimester is when it is most noticeable. It is involved in or present in the majority of IUGR patients. Preeclampsia, persistent hypertension, and uterine abnormalities are a few examples of extrinsic factors that impact the foetus later in gestation and can cause asymmetric IUGR.²

Causes of intrauterine growth restriction

Intrauterine growth restriction is caused by several factors, which are categorised as placenta, maternal, or foetal factors.

Placenta factors: 

• Placental dysfunction can seriously compromise the function of the placenta and blood flow, resulting in insufficient oxygen and nutritional supply to the growing foetus (associated with disorders like pregnancy-induced hypertension and pre-eclampsia).¹  
• Placental insufficiency happens when the placenta is unable to provide the foetus with enough oxygen and nutrition.
• Abnormalities of the placenta including placenta previa, placental abruption, and placental infarction.
• Problems with implantation or abnormal placental development.

Maternal factors:

• Chronic medical diseases such as diabetes, renal disease, autoimmune illnesses, and hypertension.
• Malnutrition in the mother, insufficient pregnancy weight growth, or a low body mass index (BMI).
• Substance misuse, which includes drinking alcohol, smoking, and using illegal drugs.
• Maternal age, either very young or old.¹

Foetal factors:

• Constitutional small (50–70% of small for gestational age (SGA) foetuses, with foetal growth appropriate for maternal size and ethnicity)
• Having multiple pregnancies
• The following congenital diseases are TORCH, malaria, congenital HIV infection, and syphilis.
• An allergy to milk (reduced milk production, foetal phenylketonuria, transient neonatal diabetes mellitus, generalised gangliosidosis type I).¹

Signs and symptoms of intrauterine growth restriction

Depending on the degree and underlying reason for intrauterine growth restriction, the signs and symptoms might change. These are some of the most common warning signs and symptoms:

• Abdominal measurements: A modest fundal height measurement, which is the distance between the pubic bone and the uterus' top, may indicate limited foetal growth.
• Women may notice reduced foetal movements or think their unborn child seems less active during pregnancy.
• The birth weight of babies with IUGR is typically lower than the expected weight at the gestational age of the child.
• Small for Gestational Age (SGA): According to ultrasound measurements, the baby's size is smaller than expected for gestational age.³
•  An unproportionate head-to-body ratio is caused by inadequate overall development, which leads to an enlarged head circumference.
• The foetus may pass meconium (its first stool) during pregnancy, which may indicate discomfort.³

Management and treatment for IUGR

IUGR is often managed and treated using a multidisciplinary approach, depending on the precise underlying cause and the severity of the illness. Here are a few IUGR management techniques that are frequently employed:

• Regular Antenatal Care: In situations with IUGR, close prenatal monitoring is essential. Regular prenatal checkups enable medical professionals to monitor maternal and foetal development and identify any potential issues early.
• Nutritional Support: For foetal development, adequate maternal nutrition is essential. Healthcare professionals may advise boosting the mother's calorie intake in IUGR situations, especially by putting an emphasis on nutrient-rich meals and making sure she gets enough protein, vitamins, and minerals.
• Doppler ultrasound: A non-invasive diagnostic technology known as Doppler ultrasound examines blood flow via the placenta and foetal arteries.
• Foetal Surveillance: In situations of IUGR, careful observation of the foetal condition is crucial. Foetal kick counts, non-stress tests (NST), biophysical profiles (BPP), and umbilical artery Doppler velocimetry are a few methods that can help with this. These examinations aid in determining the foetal heart rate, mobility, amniotic fluid levels, and general health.
• Drugs: Healthcare professionals may recommend drugs to increase foetal blood flow or placental function. Depending on the underlying aetiology of IUGR, medications like low-dose aspirin or anticoagulants may be taken into consideration.
• Neonatal Intensive Care: The infant may need specialised care in a neonatal intensive care unit (NICU) if IUGR is severe if there are indications of foetal distress. Close observation, temperature control, nutritional assistance, and handling of any related issues are all part of NICU care.
• Timing and Mode of Delivery: The choice of when and how to deliver the baby is influenced by several variables, including the gestational age, degree of IUGR, the welfare of the foetus, and the health of the mother.⁴

Diagnosis

Accurate knowledge of the baby's gestational age is one of the most crucial factors in IUGR diagnosis. Early ultrasound calculations and utilising the first day of the last menstrual period (LMP) can both be used to determine the gestational age. The following techniques can be used to diagnose IUGR after the gestational age is established.¹

• Fundal height: It is the quickest and most typical way to identify IUGR. The measurement of uterine size known as "fundal height" is the centimetre-long distance between the pubic bone and the top of the uterus. The measurement in centimetres typically correlates to the number of weeks of pregnancy after the 20th week. IUGR is suggested by a fundal height lag of 4 cm or greater.
• Weight checks: At each prenatal examination, doctors routinely determine the mother's weight and record it. A mother's inability to gain weight appropriately may be a sign that her unborn child has a growth issue.
• Ultrasound: The baby's head and abdomen are measured, and the results are compared to growth charts to determine the baby's weight. Amniotic fluid can also be detected using ultrasound.
• Doppler evaluation: This method measures the quantity and rate of blood flow via the blood arteries using sound waves. This test may be used by doctors to examine blood flow in the umbilical cord and vessels in the developing baby's brain. Doppler tests that are abnormal are indicative of IUGR.²

FAQs

How can I prevent intrauterine growth restriction

There are several steps that may be taken to lower the risk of IUGR and improve the likelihood of a healthy pregnancy and infant, even though IUGR can happen even when a mother is in excellent health.

By concentrating on women before and between pregnancies, inter-conception care enhances the health of mothers and infants. To improve weight and cardiovascular health prior to conception, it involves encouraging good food and physical activity. To enhance the health of mothers and newborns during the perinatal period, it is essential to diagnose and treat chronic conditions, including hypertension and diabetes, treat anaemia, and give folic acid supplements.²

How common is intrauterine growth restriction

IUGR is a significant global health issue for developing nations. However, in some high-risk groups, such as pregnancies complicated by maternal illnesses like hypertension, preeclampsia, or chronic diseases, as well as pregnancies with multiple gestations (such as twin or triplet pregnancies), the incidence may be greater. In these high-risk groups, the incidence of IUGR can range from 20 to 25 per cent.¹

Are there any risks of the baby being born with IUGR

Infants with IUGR are more likely to experience impaired neurodevelopment and growth outcomes as they become older and approach school age. Additionally, they are more likely to experience growth retardation, behavioural issues, poor cognitive performance, modest neurological malfunction, and cerebral palsy throughout their childhood and adolescence, which are conditions that typically manifest in adults.¹

Does IUGR cause early labour?

Intrauterine growth restriction (IUGR) occurs when a foetus is unable to grow as quickly as predicted when within the womb. One of the possible consequences is a higher chance of early labour, which is known to relate to several negative outcomes. The link between IUGR and preterm delivery is complicated, and it's crucial to remember that not all cases of IUGR result in early labour.¹

What do I do if my baby has IUGR?

If the IUGR is severe and there are signs of foetal distress, the baby may require expert care in a neonatal intensive care unit (NICU). The NICU provides care that includes close monitoring, temperature management, nutritional support, and handling of any associated problems.⁴

When should I see a doctor?

Pregnant women should have access to appropriate medical care both before and after getting pregnant. This includes promoting a balanced diet and regular exercise as well as managing chronic conditions like diabetes and hypertension. Pregnant women should take their prescribed medications, follow a healthy diet, get adequate sleep, and refrain from using cigarettes, alcohol, and other substances. Planning for delivery in locations with emergency obstetric and neonatal care services should be part of prenatal care.⁴

Summary

IUGR causes up to ten per cent of foetuses to become unable to grow to their genetically set potential size, and neonates who have undergone IUGR are subject to long-term as well as short-term health problems.