LBW

28 محرم 1435 هـ Pediatric Lec. Dr.a'ashuur
2/12/2013
Prematurity and LBW (IUGR) (SGA)
DEFINITIONS:
Live born infants delivered before 37 wk from the 1st day of the LMP are termed Premature by WHO.
LBW (< 2,500 g ) is due to:-
1- Prematurity.
2- Poor intrauterine growth (IUGR, SGA), or both.
Prematurity & IUGR ↑↑ Neonatal morbidity and mortality.

INCIDENCE:

↑ % of deaths in children < 5 yr of age that occur in the neonatal period.
38% of < 5 yr deaths occur in 1st mo of life, (1/3) due to premature birth.
Developing countries, 70% of LBW have IUGR.
IUGR Infants have greater morbidity and mortality than do appropriately grown, gestational age–matched infants.

VERY LOW BIRTHWEIGHT INFANTS:

Are infants weigh <1,500 g
Predominantly premature.
VLBW rate is accurate predictor of infant mortality rate.
VLBW infants account for
50% of neonatal deaths
50% of handicapped infants.


FACTORS RELATED TO PREMATURE BIRTH AND LBW (IUGR):
Same factors associated with prematurity & (LBW) IUGR .
Strong relation between (prematurity and IUGR) and low socioeconomic status.
Higher rates of maternal undernutrition,
Anemia
Illness;
Inadequate prenatal care;
Drug misuse;
Obstetric complications; and
Bad Maternal reproductive history (abortions, stillbirths, premature/LBW
Single-parent families,
Teenage pregnancies,
Short interpregnancy interval, and
Mothers who have borne > 4 previous children

Identifiable Causes of Preterm Birth:

1.Fetal
Fetal distress
Multiple gestation
Erythroblastosis
Nonimmune hydrops
2.Placental
Placental dysfunction
Placenta previa
Abruptio placentae
3.Uterine
Bicornuate uterus
Incompetent cervix (premature dilatation)
4.Maternal
Preeclampsia
Chronic medical illness (cyanotic heart disease, renal disease)
Infection (Listeria monocytogenes, group B streptococcus, urinary tract
infection, bacterial vaginosis, chorioamnionitis)
Drug abuse (cocaine)


Factors Often Associated with IUGR:
Fetal
Chromosomal disorders (autosomal trisomies)
Chronic fetal infections (CMV inclusion disease, congenital rubella, syphilis)
Congenital anomalies—syndrome complexes
Irradiation
Multiple gestation
Pancreatic hypoplasia
Insulin deficiency
Insulin-like growth factor type I deficiency

Placental

↓ placental weight or cellularity, or both
Decrease in surface area
Villous placentitis (bacterial, viral, parasitic)
Infarction
Tumor (chorioangioma, hydatidiform mole)
Placental separation
Twin transfusion syndrome

Maternal

Toxemia
Hypertension or renal disease, or both
Hypoxemia (high altitude, cyanotic CHD or pulmonary disease)
Malnutrition (micro- or macronutrient deficiencies)
Chronic illness
Sickle cell anemia
Drugs (narcotics, alcohol, cigarettes, cocaine, antimetabolites)


IUGR classified as reduced growth that is:
Symmetric
Asymmetric IUGR

Symmetric IUGR

Head circumference, length, and weight equally affected
Earlier onset
Seriously affect fetal cell number, such as conditions with
chromosomal,
genetic,
malformation,
teratogenic,
infectious, or
severe maternal hypertensive etiologies.

Asymmetric IUGR (with relative sparing of head growth) .

Late onset,
Preserve Doppler waveform velocity to carotid vessels
Associated with
Poor maternal nutrition or
Late onset or exacerbation of maternal vascular disease (preeclampsia, chronic hypertension).


Problems of IUGR (SGA) Infants:
PROBLEM PATHOGENESIS
Intrauterine fetal demise Hypoxia, acidosis, infection, lethal anomaly
Perinatal asphyxia ↓ Uteroplacental perfusion during labor ± chronic fetal hypoxia-acidosis;meconium aspiration syndrome
Hypoglycemia ↓ Tissue glycogen stores, ↓ gluconeogenesis, hyperinsulinism, ↑ glucose needs of hypoxia, hypothermia, large brain
Polycythemia-hyperviscosity Fetal hypoxia with ↑ erythropoietin production
Reduced oxygen consumption/hypothermia Hypoxia, hypoglycemia, starvation effect, poor subcutaneous fat stores
Dysmorphology Syndrome anomalads, chromosomal-genetic
disorders, oligohydramnios-induced deformation, TORCH infection

Infant with IUGR has:

Reduced birth weight
Disproportionately larger head relative to body size;
Infants in both groups lack subcutaneous fat.
Neurologic maturity (nerve conduction velocity), in the absence of asphyxia, correlates with gestational age

ASSESSMENT OF GESTATIONAL AGE AT BIRTH:

Physical signs useful
Ballard scoring system is accurate to ±2 wk.

An infant at high risk for mortality or morbidity if a discrepancy exists between

GA estimation by physical examination,
Mother's estimated date of her LMP
Fetal ultrasonic evaluation
Neonatal Problems Associated with Premature Infants:
Respiratory
RDS
Bronchopulmonary dysplasia
Pneumothorax,
pneumomediastinum;
Interstitial emphysema
Congenital pneumonia
Pulmonary hypoplasia
Pulmonary hemorrhage
Apnea


Cardiovascular
PDA
Hypotension
Hypertension
Bradycardia (with apnea)
Congenital malformations

Hematologic

Anemia (early or late onset)
Subcutaneous, organ (liver, cranial, adrenal) hemorrhage[*]
Disseminated intravascular coagulopathy
Vitamin K deficiency
Hydrops—immune or nonimmune

Gastrointestinal

Poor GIT function—poor motility[*]
Necrotizing enterocolitis
Hyperbilirubinemia—direct and indirect[*]
Congenital anomalies producing polyhydramnios
Spontaneous gastrointestinal isolated perforation


Metabolic-Endocrine
Hypocalcemia
Hypoglycemia
Hyperglycemia
Late metabolic acidosis
Hypothermia
Euthyroid but low-thyroxine status

Central Nervous System

Intraventricular hemorrhage
Periventricular leukomalacia
Hypoxic-ischemic encephalopathy
Seizures
Retinopathy of prematurity
Deafness
Hypotonia
Congenital malformations
Kernicterus (bilirubin encephalopathy)
Drug (narcotic) withdrawal

Renal

Hyponatremia
Hypernatremia
Hyperkalemia
Renal tubular acidosis
Renal glycosuria
Edema


PROGNOSIS:
Infants BW (1,501–2,500 g) > 95% chance of survival,
Infants BW < (1,500) significantly higher mortality .
VLBW infant is at increased risk of dying of complications of prematurity
bronchopulmonary dysplasia,
necrotizing enterocolitis, or
nosocomial infection .
Post-discharge mortality rate of LBW infants is > term infants during the 1st 2 yr of life.
Mainly by infection (RSV), they are Preventable.
In addition, premature infants have an increased incidence of
FTT
SIDS
Child abuse
Inadequate maternal-infant bonding.

Congenital anomalies present in 5% of LBW infants.

High mortality and morbidity The biologic risk associated with
Poor cardiorespiratory regulation because of immaturity or
Complications of underlying perinatal disease
Social risk associated with poverty also contribute to the.


IMMEDIATE Sequelae of LBW:
Hypoxia,ischemia
Intraventricular hemorrhage
Sensorineural injury
Respiratory failure
Necrotizing enterocolitis
Cholestatic liver disease
Nutrient deficiency
Social stress
Other
SIDS
Infections,
Inguinal hernia,
Cutaneous scars (chest tube, patent ductus arteriosus ligation, intravenous infiltration),
Gastroesophageal reflux,
Hypertension,
Craniosynostosis,
Cholelithiasis,
Nephrocalcinosis,
Cutaneous hemangiomas


LATE Sequelae of LBW:
MR,
Spastic diplegia,
Microcephaly,
Seizures,
Poor school performance
Hydrocephalus
Hearing, visual impairment,
Retinopathy of prematurity,
Strabismus,
Myopia
Bronchopulmonary dysplasia,
Cor pulmonale,
Bronchospasm,
Malnutrition,
Subglottic stenosis,
Iatrogenic cleft palate,
Recurrent pneumonia
Short-bowel syndrome,
Malabsorption,
Malnutrition,
Infectious diarrhea
Cirrhosis,
Hepatic failure,
Hepatic carcinoma,
Osteopenia,
Fractures,
Anemia,
Vitamin E,
Growth failure
Child abuse or neglect,
FTT
Divorce
Other