SGA/IUGR
Sue Ann Smith, MD
Neonatologist
Doernbecher Neonatal Care Center
Intrauterine Growth Restriction
(IUGR)
No universal definition
 Any baby who does not achieve intrauterine
growth potential
 Usually defined as < 2 SD below the mean
for weight.

Small for Gestational Age (SGA)
Usually defined as <2SD or <10th % for
growth parameters
 Babies <3% are at greatest risk of morbidity
and mortality.
 Babies who are constitutionally small are at
less risk of complications than those who
are SGA from pathologic process.

Etiology of SGA
Maternal Factors
 Placental Factors
 Fetal Factors

Maternal Factors


Genetic size
Demographics
– Age (extremes of reproductive age)
– Race
– Socioeconomic status



Underweight before pregnancy or malnutrition
Chronic disease
Exposure to teratogens (EtOH, drugs, radiation,
etc.)
Maternal Factors (cont.)
Factors that interfere with placental flow and function
 Postmaturity
 Heart disease
 Multiple gestation
 Renal disease
 Uterine anomalies
 Hypertension
 Thrombotic disease
 Pulmonary disease
 High altitude
 Hemoglobinopathies
environment
 Collagen-vascular
 Smoking
disease
 Cocaine
 Diabetes
Placental Factors






Malformations – vascular
Chorioangioma
Infarction
Abruption
Previa
Abnormal trophoblast invasion
Fetal Factors
Constitutional – genetically small, but
genetically normal
 Chromosomal abnormality – only about 5%
of SGA babies
 Malformations – CNS, skeletal,
gastroschisis
 Congenital infections – CMV, rubella

Characteristics of IUGR
Symmetric






Early onset
Constitutional or “normal” small
Decreased growth potential
Normal ponderal index
Lower risk for transitional problems
Brain symmetrical to body
Examples



Genetic causes, chromosomal
TORCH infections
Anomalad Syndromes
Characteristics of IUGR
Asymmetric
 Late onset
 Environmental
 Growth arrest
 Higher risk for transitional problems
 Brain sparing
Examples
 Chronic hypoxia
 Preeclampsia (PIH, PET)
 Chronic hypertension
 Malnutrition
Neonatal Complications of IUGR
 Mortality
rate 5-20x that of AGA
 Perinatal asphyxia
 Abnormal temperature regulation
 Hypoglycemia
 Hyperviscosity-polycythemia syndrome
 Altered immunity
 Thrombocytopenia
Neonatal Complications of
IUGR(cont)
 Pulmonary
hemorrhage
 PPHN
 Hypocalcemia
Evaluation of SGA Newborn





Careful physical examination
Measure & plot head circumference &
length
CBC with differential and platelet count
Monitor glucose carefully
Further evaluation?
–
–
–
–
Urine for CMV
TORCH titers
Liver function tests
Head Ultrasound
“Long term” Morbidity of IUGR
Factors associated with abnormal outcome
?
 Microcephaly
 Hypoxic ischemic encephalopathy
 Symptomatic hypoglycemia
 Symptomatic hyperviscosity
Growth Consequences of IUGR
Weight at 4 years
50
50
40
40
Percent
Percent
Height at 4 years
30
20
10
30
20
10
<10 10-50 50-90 >90
<10 10-50 50-90 >90
Percent
Percent
Term AGA
Term SGA
Preterm SGA
Growth Consequences of IUGR
Head Circumference at 4 years
50
40
30
20
10
Percent
Term AGA
<10 10-50 50-90 >90
Term SGA
Preterm SGA
Fetal Origins of Adult Diseases ?
Coronary artery disease correlates
inversely with birth weight
 Rate of non-insulin dependent diabetes
mellitus is highest in the “thinnest” babies
at birth (low ponderal index)
 High serum cholesterol are linked to
disproportionate size at birth (body smaller
than head)
 Increased rate of hypertension in infants
who were thin, short, &/or proportionately
small at birth
