18. Intrauterine growth retardation (IUGR)

Question 1

what is IUGR?

Answer 1

a fetus that has not reached its growth potential because of genetic or environmental factors

Question 2

what is Small for gestational age (SGA)?

Answer 2

an infant whose birth weight is below the 10th percentile for the appropriate gestational age.

not the same as IUGR

Question 3

Low birth weight (LBW) ?

Answer 3

defined as a birth weight < 2500 g, regardless of gestational age.

Question 4

The causes of IUGR are divided into?

Answer 4

maternal, placental and fetal factors

Question 5

what are the maternal factors for IUGR?

Answer 5

• Chronic illness (diabetes, HTN, CKD, APS, anemia, heart disease, pulmonary disease)
• Preeclampsia
• Early or advanced age
• Malnutrition
• Uterine anomalies
• Substance abuse (smoking, alcohol, narcotics, cocaine)
• Medications (warfarin, anticonvulsants)

Question 6

what are the placental factors for IUGR?

Answer 6

• Uteroplacental insufficiency
• Abnormal implantation
• Vascular anomalies
• Placental abruption
• Placental infarction
• Chorioamnionitis
• Confined placental mosaicism

Question 7

what are the fetal factors for IUGR?

Answer 7

• Chromosomal disorders
• Congenital anomalies
• Multiple gestations (TTTS)
• Infections (TORCH, varicella, malaria)
• Metabolic disorders (PKU, galactosemia)

Question 8

how do we diagnose IUGR?

Answer 8

based on discrepancies between actual and expected sonographic biometric measurements for a given gestational age.
defined as < 10th percentile weight for gestational age on a singleton growth curve.

• if theres uncertainty between IUGR true diagnosis vs. incorrect pregnancy dating → check results of previous prenatal US.

Question 9

what types of monitoring is indicated if the the fetus <10th percentile weight gestational age is identified?

Answer 9

1. Accurate assessment of gestational age
2. Symphysis‐fundal height measurement
3. Non-stress test (NST)
4. Biophysical profile (BPP) → NST, AFI, muscle tone, respiration, fetal movements
5. Oxytocin challenge test (OCT)
6. Ultrasound screening and diagnosis
7. Fetal genetic studies may be considered in some cases (US studies, NIPT, genetic amniocentesis)

Question 10

what are the US screenings for diagnosis of IUGR?

Answer 10

*Head: biparietal diameter, occipitofrontal diameter, head circumference
*Abdominal circumference (the most sensitive indicator for symmetric and asymmetric IUGR)
*Femur length
*Estimated fetal weight (EFW)
*HC/AC ratio (head circumference/abdominal circumference)
*FL/AC ratio (femur length/abdominal circumference)
*Transverse cerebellar diameter
*Amniotic fluid: AFI 5-24 cm or deepest pocket 2-8 cm (first US sign to be abnormal)
*Doppler evaluation: uterine arteries, umbilical arteries (Doppler velocimetry), descending aorta, MCA

Question 11

what is the most sensitive indicator for symmetric and asymmetric IUGR?

Answer 11

abdominal cicumference

Question 12

symmetric IUGR cases

Answer 12

1.20-30%
2. occurs early in pregnancy
3. Head circumference, length, and weight all ↓ proportionally (HC/AC ratio usually normal).

Question 13

asymmetric IUGR cases

Answer 13

1.70-80%
2. occurs late in pregnancy (3rd trimester)
3. Head circumference is spared relative to ↓ weight, length, and/or abdominal circumference (HC/AC ratio usually increased).

Question 14

what causes symmetric IUGR?

Answer 14

an intrinsic insult (genetic) or 1st-trimester insult (infection) that interfere with early fetal cellular hyperplasia, producing uniformly reduced growth.

Question 15

what causes asymmetric IUGR?

Answer 15

adaptation to a hostile environment by redistributing blood flow in favor of vital organs (brain, heart, adrenals) at the expense of non-vital fetal organs (viscera, liver, kidneys, limbs).

Question 16

management of IUGR

Answer 16

1. If NST is non-reassuring or umbilical artery diastolic flow is reversed or absent → the fetus should be delivered immediately.
2. For those left undelivered, frequent antenatal testing (NST, BPP, US) is recommended.
3. Antenatal corticosteroids to accelerate fetal lung maturity; and, possibly, admission to the hospital for continuous monitoring.
4. Maternal interventions – approaches to be considered: maternal nutritional supplementation, oxygen therapy, and interventions to improve blood flow to the placenta (plasma volume expansion, low-dose aspirin, bed rest, anticoagulation, and PDE-5 inhibitors).

Question 17

short term neonatal complications for IUGR

Answer 17

• Prematurity (increased risk for preterm delivery)
• Hypoglycemia
• Hypothermia (impaired thermoregulation)
• Polycythemia and hyperviscosity (↑ EPO production secondary to fetal hypoxia)
• Perinatal asphyxia
• Jaundice
• Increased susceptibility to infections and neonatal sepsis

Question 18

Long-term consequences of IUGR

Answer 18

1. symmetric IUGR –> permanent growth restriction.
2. asymmetric IUGR–> more likely to experience catch-up growth under optimal childhood conditions (usually by the second year of life).
   *In the absence of congenital abnormalities or central nervous system injury!
3. increased risk for neurodevelopmental abnormalities including decreased cognitive performance, ADHD, school difficulties, and minor neurologic dysfunction.
4. contributing factor for adult chronic diseases including coronary artery disease, hyperlipidemia, hypertension, and chronic kidney disease.