Intrauterine Growth Restriction(IUGR)

Overview:

Intrauterine growth restriction (IUGR) refers to the poor growth of a baby while in the mother's womb during pregnancy. The terms “IUGR” and “small for gestational age (SGA)” have been used synonymously in medical literature, but there exist small differences between the two. SGA definition is based on the cross-sectional evaluation (either prenatal or postnatal), and this term has been used for those neonates whose birth weight is less than the 10th percentile for that particular gestational age or two standard deviations below the population norms on the growth charts, and the definition considers only the birth weight without any consideration of the in-utero growth and physical characteristics at birth. An IUGR is a clinical definition and applies to neonates born with clinical features of malnutrition and in-utero growth retardation, irrespective of their birth weight percentile. 

1. Etiology: 

Many different things can lead to intrauterine growth restriction (IUGR). An unborn baby may not

get enough oxygen and nutrition from the placenta during pregnancy because of: 

• High altitudes 

• Multiple pregnancy (twins, triplets, etc.) 

• Placenta problems 

• Preeclampsia or eclampsia 

Problems at birth (congenital abnormalities) or chromosome problems are often associated with

below-normal weight. Infections during pregnancy can also affect the weight of the developing baby. These include: 

• Cytomegalovirus 

• Rubella 

• Syphilis 

• Toxoplasmosis 

2. Risk factors:

In the mother that may contribute to IUGR include: 

• Alcohol abuse 

• Smoking 

• Drug addiction 

• Clotting disorders 

• High blood pressure or heart disease 

• Kidney disease 

• Poor nutrition  

If the mother is small, it may be normal for her baby to be small, but this is not due to IUGR. 

Depending on the cause of IUGR, the developing baby may be small all over. Or, the baby's

head may be normal size while the rest of the body is small.  

3. Effects on Neonate: 

If growth restriction is caused by placental insufficiency and, therefore, malnutrition, the infant’s weight is most affected, with a relative sparing of growth of the brain, cranium, and long bones  
(asymmetric growth restriction). 

4. Prognosis: 

If asphyxia can be avoided, neurologic prognosis is quite good. 

Infants who are SGA because of genetic factors, congenital infection, or maternal drug use often have worse prognosis, depending on the specific diagnosis. If intrauterine growth restriction is caused by chronic placental insufficiency, adequate nutrition may allow SGA infants to demonstrate remarkable “catch-up” growth after delivery. 

5. Complications: 

a. Perinatal asphyxia is the most serious potential complication. It is risk during labor if intrauterine growth restriction is caused by placental insufficiency (with marginally adequate placental perfusion), because each uterine contraction slows or stop maternal placental perfusion by compressing the spiral arteries. If fetal compromise is detected, rapid delivery, often by cesarean section, is indicated 

• Increased Respiratory Complications: 

IUGR babies are often born prematurely (even if they are technically full term), which can lead to underdeveloped lungs. 

• IUGR is associated with poor lung development and an increased likelihood of respiratory distress syndrome (RDS), pulmonary hypertension, and mechanical ventilation needs. 

The underdevelopment of the lungs, particularly in babies with asymmetric IUGR, leads to challenges in oxygenation and ventilation, requiring RTs to manage respiratory support with oxygen therapy, CPAP, or mechanical ventilation. 

• Increased Risk for Meconium Aspiration: 

IUGR infants are at higher risk for meconium aspiration syndrome (MAS) due to intrauterine stress. In these cases, the baby may inhale meconium into their lungs during or after delivery, requiring careful respiratory management, including suctioning, monitoring, and sometimes mechanical ventilation. 

• Higher Likelihood of Hypoxia and Acidosis: 

IUGR babies may experience periods of hypoxia (low oxygen levels) and acidosis (low blood pH), which can lead to respiratory distress. RTs must be prepared to support the baby’s respiratory efforts, correct blood gas abnormalities, and provide optimal oxygenation and ventilation. 

• Need for Close Monitoring: 

IUGR babies require more frequent and detailed monitoring of their oxygen saturation, heart rate, and breathing patterns. Respiratory therapists need to monitor for signs of respiratory failure, initiate appropriate interventions, and coordinate with the neonatology team. 

Blood gas analysis may be necessary to assess oxygenation and ventilation, and RTs should be familiar with how to interpret these and adjust respiratory settings accordingly 

What respiratory therapists need to be prepared for with IUGR babies: 

a. Respiratory Support: 

•  Continuous Positive Airway Pressure (CPAP): Used to help keep the lungs inflated and reduce the work of breathing, especially if there is an underdeveloped surfactant system or pulmonary hypoplasia. 

• Mechanical Ventilation: Some IUGR babies may need intubation and mechanical ventilation, especially if they experience severe respiratory distress or inadequate oxygenation. 

• Oxygen Therapy: Supplemental oxygen might be required to maintain adequate oxygen saturation, and RTs need to ensure the appropriate oxygen delivery method, such as nasal cannulas, CPAP, or high-flow nasal cannula. 

b. Surfactant Replacement Therapy: 

• Surfactant deficiency is common in IUGR babies, particularly if they are preterm or have immature lungs. RTs should be familiar with the indications for surfactant therapy and the procedures for administering it, either through intubation or via non-invasive methods (in some cases). 

c. Monitoring and Troubleshooting: 

• Regular assessment of respiratory rate, oxygen saturation, and heart rate is essential. RTs must also monitor for signs of apnea of prematurity, bradycardia, or cyanosis. 

• RTs should be prepared to recognize and manage mechanical ventilator issues, such as ventilator-associated lung injury (VILI) or the need for adjustments in settings based on the baby’s condition and gas exchange. 

d. Understanding Long-Term Risks: 

• UGR babies are at higher risk for developing chronic lung disease (CLD) or bronchopulmonary dysplasia (BPD), particularly if they have prolonged ventilation or oxygen requirements. RTs need to provide ongoing respiratory support and monitor for signs of CLD as the infant grows. 

• IUGR can also affect neurodevelopmental outcomes and increase the risk of conditions like cerebral palsy and developmental delays, which may require additional multidisciplinary interventions and follow-up care.