The Small forThe Small for Gestational Age Infant

Perinatology DivisionPerinatology DivisionDepartment of Child Health Medical SchoolMedical SchoolUniversity of Sumatera Utara

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S ll F G t ti l A (SGA)Small For Gestational Age (SGA)Definition

Birth weight or birth crown heel length

Definition

Birth weight or birth crown-heel length <2 SD for gestational age, based on data derived from a reference populationderived from a reference population SGA has also been defined as birth weight or length below the 10th 5th or 3rdor length below the 10th, 5th, or 3rd percentile for gestational age

2International SGA Advisory Board Consensus Development Conference Statement: PEDIATRICS Vol. 111 No. 6 June 2003, pp. 1253-1261

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SGA IUGRSGA vs. IUGR

SGA d IUGR tSGA and IUGR are not synonymousSGA refers to the size of the infant at birth and not fetal growthIUGR suggests diminished intrauterine gggrowth velocityIUGR indicates the presence of aIUGR indicates the presence of a pathologic process in-utero that inhibits fetal growth

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fetal growth

SGA IUGRSGA vs. IUGR

A child who is born SGA is not always IUGR Infants born after a short period of IUGR are not always SGA ySGA:

IUGRIUGRConstitutionally small infant

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F t l G thFetal Growth

Up to 20 wk, fetal growth is due primarily to increase in cell number with rapid mitosis and an increase in DNA content (hyperplastic stage)20-28 wk: declining mitosis and an increase in cell sizeAfter 28 wks: rapid increase in cell size and accumulation of fat, muscle and

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and accumulation of fat, muscle and connective tissue (hypertrophic stage)

Fetal GrowthFetal Growth

Eighty-five percent of fetal weight gain occurs during the second half of pregnancyFat deposition mainly in 3rd trimester Fetal weight gain is constant in 1st and 2nd trimesters2 trimestersFetal weight gain accelerates in 3rd

trimester and then declines near term7

trimester and then declines near term

Etiology M t l f t1. Maternal factorsReduced uteroplacental blood flowP l i l iPreeclampsia-eclampsiaChronic renovascular diseaseCh i h t i l diChronic hypertensive vascular diseaseMaternal MalnutritionM lti lMultiple pregnancyMaternal hypoxemia

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Maternal factorsDrugsCigarettes: Infants of smokers weigh 150g g g gto 200g less than non-smokersAlcohol abuse: Fetal alcohol syndromeAlcohol abuse: Fetal alcohol syndromeHeroin/cocaine/methamphetamines:

55% of neonates born to heroin55% of neonates born to heroin addicted mothers weigh <2500g

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Antiepileptics, Antimetabolites, Steroids,

Others maternal factorsMaternal short statureYoung maternal ageg gShort interpregnancy intervalUterine anomaliesUterine anomaliesLow sosioeconomic classPrimiparityGrand multiparity

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2. Placental FactorsUtero-placental insufficiency resulting from:

I / i d t t h bl tiImproper / inadequate trophoblastic invasion and placentation in the first trimesterAberrant placental insertionAberrant placental insertionReduced maternal blood flow to the placental bed (thrombosis infarctsplacental bed (thrombosis, infarcts, hemangioma)

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Placental FactorsPlacental Factors

Feto-placetal insufficiency due to:Vascular anomalies of placenta andVascular anomalies of placenta and cordD d l t l f ti iDecreased placental functioning mass:

Small placenta, abruptio placenta, placenta previa, post term pregnancy.

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p g y

3 Fetal Factors3. Fetal Factors

G tiGenetic Chromosomal anomalies:10% of SGA i f tinfantsCongenital malformationsCongenital infection: TORCHFetal cardiovascular anomaliesInborn error of metabolism

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ClassificationClassification

SymmetricalSymmetrical AAsymmetricalsymmetrical

Baby's head and length are preserved

Baby's head and body are proportionately small preserved

Occur when the fetus

proportionately small

May occur when the fetus experiences a problem later in pregnancy

experiences a problem during early development

I l i f t th b i i h b t th ti th th li II l i f t th b i i h b t th ti th th li I

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In a normal infant, the brain weighs about three times more than the liver. In In a normal infant, the brain weighs about three times more than the liver. In asymmetrical IUGR, the brain can weigh five or six times more than the liver.asymmetrical IUGR, the brain can weigh five or six times more than the liver.

Types of SGA / IUGRSymmetric IUGR

Type IAsymmetric IUGR

Type II

yp

Early onset growth restrictionU if th

Late onset growth restriction

Uniform growth restrictionLong-term growth f il

Head SparingPotentially reversibleAssociated withfailure

Associated with decreased cell number

Associated with decreased cell sizeInfants demonstrate

Associated with less catch-up growth in the first year of life

more catch-up growth than symmetric IUGR in first year of life

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first year of life in first year of life

DiagnosisDiagnosisAntenatal

Presence of risk factorsInadequate growth detected by serialInadequate growth detected by serial measurement of weight, abdominal girth and fundal heightand fundal heightUltrasound evaluation of fetal growth

I d t f t l thInadequate fetal growthPlacental calcification

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Di iDiagnosis

N t lNeonatalLow ponderal index ([weight(g)/length³ (cm)] x 100) Decreased subcutaneous fat with soft ec eased subcu a eous a sotissue, desquamated skin, meconium stainedWidened cranial sutures with large fontanelles

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fontanelles

NeonatalThin umbilical cordSkin and sole creases more mature than GA‘‘alert-looking’’ and jitteryalert looking and jitteryCongenital malformationsStigmata of congenital infectionsStigmata of congenital infections

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Neonate and Placenta in IUGR

Normal & IUGR N b b biNewborn babies

Normal & IUGR Placentas

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Small for gestational ageg g

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Problems Associated With Impaired Fetal Growth

Short-term morbidityLong-term outcomes

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Sh t t biditShort-term morbidityStill birthStill birthPrematurityF t l di t i l bFetal distress in laborMASPerinatal depression / AsphyxiaPersistent Pulmonary HypertensionPersistent Pulmonary HypertensionRDS

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Short term morbidityShort-term morbidity

H l i 12 24%Hypoglycemia: 12-24% Hyperviscosity-polycythemia Syndrome: 15-17%Poor ThermoregulationgHypocalcemiaThrombocytopenia/NeutropeniaThrombocytopenia/NeutropeniaPoor humoral and cellular immunity

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NEC

L t biditLong term morbidity

Cognitive & Neuro-developmental outcomeoutcomeEffects on childhood growthP di iti t d lt t diPredisposition to adult onset diseases

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Cognitive & Neuro DevelopmentalCognitive & Neuro-Developmental Outcome

Strong association between poor prenatal head growth (symmetric IUGR) and poor developmental outcome However, neurodevelopmental outcome in infants with ‘fetal brain sparing’ (asymmetrical IUGR) is less clear cut( y )

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PreventionPrevention Prenatal intervention strategies include:

P t i / l t tiProtein/energy supplementation Treatment of anaemiaVitamin/mineral supplementation Fish oil supplementationFish oil supplementationPrevention and treatment of

Hypertensive disordersHypertensive disorders, Fetal compromise Infection

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Infection

P tiStrong evidence of benefit only for the

PreventionStrong evidence of benefit only for the following interventions:

Balanced protein/energyBalanced protein/energy supplementationSt t i t d t l kiStrategies to reduce maternal smoking, Treatment of TB and urinary tract infectionsAnti-malarial prophylaxis

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p p y

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