iugr and sga

DR Laxman Singh Charan Neonatal division Department of Pediatrics Safdarjang Hospital

Definitions

IUGR: Failure of normal fetal growth caused by multiple adverse effects on the fetus.

SGA: Infant with wt < 10% ile for GA, or > 2 SDs below mean for GA.

Easiest way to think about these terms are

IUGR: is a term used by Obstetricians to describe a pattern of growth over a period of time.

SGA: is a term used by Pediatrician to describe a single point on a growth curve.

IncidenceIn india.3 - 10 % of all pregnancies.20 % of stillborns are growth retarded.30 % of infants with SIDS were IUGR.1/3 of infants with BW < 2800 grams are growth

retarded and not premature.9 - 27 % have anatomic and/or genetic abnormalities.Perinatal mortality is 8 - 10 times higher for these

fetuses.

Types of IUGRSymmetric IUGR: weight,length and head

circumference are all below the 10th percentile. (33 % of IUGR Infants)

Asymmetric IUGR: weight is below the 10 th percentile and head circumference and length are preserved. (55 % of IUGR)

Combined type IUGR: Infant may have skeletal shortening, some reduction of soft tissue mass.(12% of IUGR)

Ponderal IndexWay of characterizing the relationship of height to

mass for an individual.

PI = 100 x

Typical values are 2.0 to 2.5PI is normal in symmetric IUGR.PI is low in asymmetric IUGR.

Mass (gm) Height (cm)3

Normal Intrauterine Growth patternStage I (Hyperplasia)

- 4 to 20 weeks

- Rapid mitosis

- Increase of DNA contentStage II (Hyperplasia & Hypertrophy)

- 20 to 28 weeks

- Declining mitosis.

- Increase in cell size.

Normal Intrauterine Growth patternStage III ( Hypertrophy) - 28 to 40 weeks - Rapid increase in cell size. - Rapid accumulation of fat, muscle and

connective tissue.95% of fetal weight gain occurs during last 20 weeks of

gestations.

EtiologyGrowth inhibition in stage I: - Undersized fetus with fewer cells. - Normal cell size.

Result in symmetric IUGR.Associated conditions:

- Genetic - Congenital anomalies - Intrauterine infections - Substance abuse - Cigarette smoking - Therapeutic irradiation

EtiologyGrowth Inhibition in Stage II/III

-Decrease in cell size and fetal weight

- Less effect on total cell numeric, fetal length, head circumferance.

Result in asymmetric IUGR.

Associated Conditions:

- Uteroplacental insufficiency.• Combination above associated mixed type IUGR.

Pathophysiology(1) Fetal factors:Genetic Factors:

- Race, ethnicity, nationality- sex ( male weight 150 -200 gm more than female )- parity ( primiparous, weight less than

subsequent siblings) -genetic disorders ( Achondroplasia,

Russell-silver syndrome.)Chromosomal anomalies:

- Chromosomal deletions - trisomies 13,18 & 21

PathophysiologyCongenital malformations:

Anencephaly, GI atresia, potter’s syndrome, and pancreatic agenesis.Fetal Cardiovascular anomaliesCongenital Infections:

mainly TORCH infections.Inborn error of metabolism:

- Transient neonatal diabetes- Galactosemia - PKU

Pathophysiology(2) Maternal Factors:Decrease Uteroplacental blood flow:

- Pre eclampsia / eclampsia- Chronic renovascular disease- Chronic hypertension

Maternal malnutritionMultiple pregnancyDrugs

- Cigarettes, alcohol, heroin, cocaine- Teratogens, antimetabolites and

therapeuticagents such as trimethadione, warfarin, phenytoin

PathophysiologyMaternal hypoxemia

- Hemoglobinopathies - High altitudes

• Others- Short stature- Younger or older age (<15 and >45)- Low socioeconomic class- Primiparity- Grand multiparity- Low pregnancy weight- Previous h/o preterm IUGR baby

- Chronic illness ( DM, renal failure, cyanotic heart- disease etc.)

Pathophysiology(3) Placental Factors:Placental insufficiency (most importent in 3rd

trimester)Anatomic problems:

Multiple infarctsAberrant cord insertionsUmbilical vascular thrombosis & hemangiomasPremature placental separationSmall Placenta

Postnatal AssessmentGrowth parameters- weight, height, HCAssess GA-with Ballard score.Growth chart -Plotted growth parameters in growth chart.

Physical appearance:

• Heads are disproportionately large for their trunks and extremities

• Facial appearance has been likened to that of a “wizened old man”.

• Long nails.• Scaphoid abdomen

• Signs of recent wasting- - soft tissue wasting - diminished skin fold thickness - decrease breast tissue - reduced thigh circumference

• Signs of long term growth failure- - Widened skull sutures, large fontanelles - shortened crown – heel length - delayed development of epiphyses

• Comparison to premature infants,IUGR has brain and heart larger in proportion to the body weight, in contrast the liver, spleen, adrenals and thymus are smaller.

ComplicationHypoxia

- Perinatal asphyxia- Persistent pulmonary hypertension- meconium aspiration

Thermoregulation- Hypothermia due to diminished subcutaneous fat and elevated surface/volume ratio.

ComplicationsMetabolic

- Hypoglycemia

- result from inadequate glycogen stores.

- diminished gluconeogenesis.

- increased BMR- Hypocalcemia

- due to high serum glucagon level, which stimulate calcitonin excretion.

ComplicationsHematologic

- Hyperviscosity and polycythemia due to increase erythropoietin level secondary to hypoxia

Immunologic- IUGR have increased protein catabolism and decreased in protein, prealbumin and immunoglobulins, which decreased humoral and cellular immunity.

ManagementAntenatal diagnosis and management is the key to proper

management of IUGRDelivery and Resuscitation

- appropriate timing of delivery- skilled resuscitation should be available- prevention of heat loss

Hypoglycemia

- close monitoring of blood glucose- early treatment ( IV dextrose,early feeding)

ManagementHematological Disorder

- Hematocrit to detect polycythemia- CBC with differential to rule out leukopenia or thrombocytopenia

Congenital infection- Infant should be examined for signs of congenital infection (eg.rash, microcephaly hepatosplenomegaly, lymphadenopathy, cardiac anomalies etc….)- TORCH titer screening- Examination of urine, nasopharynx- Head CT to rule out calcification

ManagementGenetic anomalies

- screening as indicated by physical exam- chromosomal analysis (infant with

dysmorphic features)Others

- serum calcium to r/o hypocalcemia- fractionated bilirubin secondary to polycythmia. congenital infection- urine,meconium for substance abuse

ManagementEarly feeding and caloric intake should be 100-120

kcal/kg/dDevelopmental and growth f/u in all IUGR infants

OutcomeSymmetric vs. Asymmetric IUGR

- symmetric has poor outcome compare to asymmetric

Preterm IUGR has high incidence of abnormalitiesIUGR with chromosomal disease has 100% incidence

of handicapCongenital infection has poor outcome - handicap

rate > 50%IUGR has higher rate of learning disability.

FOLLOW-UPIUGR babies are risk for poor growth and neuro-

developmental outcome.Routinely follow IUGR babies with birth weight below 3rd

centile and those with birth weight 3-10th centile if they develop significant morbidities (e.g. hypoglycemia, polycythemia,birth asphyxia) during hospital stay.