THE LOW BIRTH WEIGHT INFANT

Julniar M TasliHerman Bermawi

1. Student must be able to understand the definition and classification of low birth weight infant. 2. Student must be able to recognize risk factor which predispose of low birth weight infant3. Student must be able to diagnose low birth weight infant4. Student must be able to manage low birth weight infant

OBJECTIVE

NEWBORN INFANT CLASSIFED ACCORDING TO :Birthweight # < 2500 g : Low birthweight (LBW) # < 1500 g : Very low birthweight (VLBW) # < 1000 g : Extremely low birthweight (ELBW)Gestational age # < 37 weeks : Preterm # 42 weeks : Post termSize for gestasional age # Weight beween 90th & 10th centile for gestation # Weight < 10th centile for gestation # Weight > 90th centile for gestation

FIGURE 3-2. Classification of newborns (both sexes) by intrauterine growth and gestational age. (Reproduced, with permission, from Battaglia FC, Lubchenco LO: A practical lassification for newborn infants by weight and gestational age. J Pediatr1967;71:159; and Lubchenco LO et al: Intrauterine growth in length and head circumference as estimated from live births at gestational ages from 26 to 42 weeks. Pediatrics 1966;37:403. Courtesy of Ross Laboratories, Columbus, Ohio 43216.)

THE LOW BIRTH WEIGHT INFANT

Definition :A low birth infant baby is one who weigh less than 2500 gram at birth The low birth infant divided into two clinical types : 1. The preterm infant ( prematurity ) 2. The small for gestational age infant ( small for dates, light for dates )

Premature or preterm : # A baby born before the 37th week of pregnancy. # May not br ready to live outside the uterus and may have difficulty initiating breathing, sucking, figting infection and stay warm. Small for gestational age( SGA ) : # A baby who did not grow well enough in the uterus during fregnancy. # The babby usually full-term and often abble breath and suck well.

FACTOR ASSOSIATED WITHLOW BIRTH WEIGHTFregnancy in women who : # Are less than 20 # Have birth that are less than 3 year apart or have many fregnancy ( five or more ) Women who : # Had a LBW baby before # Are under weight and have poor nutrition. # Have health problem ( hypertension, anemia )

FACTOR ASSOSIATED WITHLOW BIRTH WEIGHTWomen who have pregnancy problem such as : # Severe anemia # Pre-eclampsia or hypertension # Infection during pregnancy ( bladder and kidney infection, HIV/AID, malaria ) # Multiple gestation

Babies who have : # Congenital or genetic abnormalities # An infection while in uterus ( TORCHs infection )

THE PRETERM INFANT ( PREMATURITY ) WHO defines a preterm birth : < 37 completed weeks gestation (< 259 days).

Incidence of preterm deliveries : ?

33% small for gestational age, have different problems from the appropriate for gestational age preterm infant.

The paediatrician have an objective test for ditermine : # Gestational age : New Ballard examination # Size for gestational age : Lubchenco chart

CLINICAL CHARACTERISTIC Skin : Maybe reddenes. The skin may thin so blood vesel are easiliy see. Lanugo : There is a lot of this fine hair all over the babys body3. Limbs : The lim are thin and may be poorly flexed or floopy due to muscle toneHead size : The head appears large in proportion to the body. Fontanella are smooth and flat5. Genital : Male, the testes may not be descended and scrtum may be small. Female, The clitoris and labia minora may be largeSole of feet : Creased are located only in the anterior t hird of the sole, not all over, as in term newborn

SPECIFIC PROBLEMS Birth asphyxiaThermal instabilityLack of primitive survival reflexes, suck, swallow, and gag with high incidence of milk aspiration.JaundicePulmonary disease : apnoe, hyaline membrane disease, transient tachypnoea of newborn, pneumothorax, pneumonia, Wilson-Mikity syndrome and bronchopulmonary dysplasia.Metabolic disturbances: hypoglycaemia, hypocalcaemia, hypomagnesaemia, hyponatraemia, hypernaetremia.

Patent ductus arteriosus : congestive heart failure.Intracranial haemorrhage, especially intraventricular haemorrhage and subarachnoid haemorrhage.Susceptibility to infectionGastrointestinal intolerance and necrotizing enterocolitisOpthalmic problems : retrolental fibroplasia, myopia, strabismusSurgical lesions : undescended testes, inguinal and umbilical herniaeHaematological problems : haemorrhagic disease of prematurity, disseminated intravascular coagulation, iron deficiency anaemiaRenal immaturity : inability to concentrate urine, and inability to excrete an acid load with low renal bicarbonate threshold results in late (feeding) metabolic asidosis .

SUPORTIVE CAREResuscitationThe Obstetrician and Paediatrician should ideally function as a perinatal team during premature labour appropriate assessment of perinatal asphyxia and resuscitation can be performed.

Monitoring Heart rate and respiratory rate, blood pressure and temperature must be monitored continuously

MonitoringTotal intake-output of fluids should be recorded every 24 hours in critically ill infants.Head circumference is measured twice weekly and plotted on a percentile graph.Daily weights are measured and recorded.

ThermoregulationBody temperature must be maintained in the normal range (36,5-37,0C per axilla) by nursing infant in incubator.

FeedingInfants < 34 weeks gestation should be fed via an oro-gastric/naso-gastic tube.Prematures with small gastric volumes require frequent feeding (every 2 hours) and should be started on 2ml/kg/feed and increased in increment of 1-2ml/kg/every feed, as tolerated.Gastric aspirate must be checked before the next feed.The preterm infant should ideally be fed his own mothers expressed breast milk.

Parenteral fluidsSick babies and infants < 1500 g may need parenteral feeding Parenteral fluid requirements can only be determined by close observation of urine-output, urine osmolality, body weight and electrolytes.In general, fluid volumes for healthy preterm infants given enterally are: 60ml/kg-day 1; 80ml/kg-day 2; 100ml/kg-day 3; 120ml/kg-day 4; 140ml/kg-day 5; 160ml/kg-day 6; 180ml/kg-day 7.

ElectrolytesPreterm infants receiving parenteral fluids should receives maintenance electrolytes after they have passed urine.Normally they require: sodium 2,5-3,0 mmol/kg/day; potassium 2,0-2,5 mmol/kg/day; calcium 300mg/kg/day.

VitaminsA single intramuscuar dose 0,5 1,0 mg IMPreterm babies being fed with breast milk or vitamin fortified formulae will all need additional vitamin C (by day 3) and vitamin D.

Respiratory Distress Syndrome (RDS)RDS should be managed with humidified oxygen given in a controlled fashion via a head box or mechanical ventilation.Babies of birthweight < 2000g with RDS should be managed in an intensive care nursery.

JaundiceExtremely common in the preterm infant and must be followed with frequent bilirubin estimations.The treatment sheet provides guidelines for management of hyperbilirubinaemia.

AnemiaThe venous haematocrit should be maintained at > 40% in all sick babies.All preterm infants < 2500 g or 34 weeks gestation should receive supplemental iron in a dose of 30 mg daily from the age of three weeks.

THE SMALL FOR GESTASIONAL AGE INFANT INSIDENVaries between countries, usually : 3-7% of all infants are SGA 20% of stillborn infants are SGA 25% of SGA Infants are Type I 75% of SGA infants are type II

AETIOLOGY

The causes SGA infants can be classified as extrinsic and intrinsic in origin1. ExtrinsicExtrinsic mechanisms operate during the latter half of pregnancy and may be associated with placental insufficiency. Fetal growth is affected because of inadequate supply line of nutriens and/or oxigen.

a. Maternal Factors # Maternal hypertension e.g. essential, pregnancy induced, renal. # Vascular disease, e.g. DM, cardiac, renal, sickle cell and collagen disease # Smoking, narcotic abuse

b. Placental and uterine factors # Abnormal placentation # Placental infarct, fibrosis, haemangioma # Premature placental separation # Single umbilical artery # Uterine crowding e.g. multiple pregnancy, uterine abnormalities

2. IntrinsicThe intrinsic group implies that there is something wrong with the fetus at the time of conception or during the first semester. a. Constitutional e.g. parental stature, racial, ethnic b. Chromosomal anomaly e.g. Trisomy 13, 18, 21, Turners Syndrome c. Fetal infections e.g. TORCH d. Maternal drugs e.g. chronic alcoholism, cytotoxic, heroin addiction e. Primordial dwarf, e.g. achondroplasia, russel Silver Dwarf

CLINICAL FINDING

IUGR can be suspected by: poor maternal weight gain, suboptimal uterine growth, low or falling oestriol levels, reduced growth of biparietal diameter on serial USGPhysical apperanceof babies in the intrinsic groupwill be characteristic of the spesific aetiology e.g. Toxoplasma, rubella, achondroplasia

The growth failure in the extrinsic group is greatest for weight, then length and head circumference is least affected. There is little subcutaneous fat, the skin may be loose and thin, muscle mass is decreased, especially buttock and thighs, and the infant often exhibit wide eye, anxious faces.

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

SGA VS IUGRA child who is born SGA is not always IUGR Infants born after a short period of IUGR are not always SGA SGA: IUGRConstitutionally small infant

Types of SGA infata. Symmetric: Weight, head circumference and length all < 2SDb. Asymmetric: Weight below 2 SD, but head circumference and length preserved

Classification SymmetricalAsymmetricalBaby's head and length are preserved

Occur when the fetus experiences a problem later in pregnancyBaby's head and body are proportionately small

May occur when the fetus experiences a problem during early developmentIn 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.

Symmetric IUGRType I

Early onset growth restrictionUniform growth restrictionLong-term growth failureAssociated with decreased cell numberAssociated with less catch-up growth in the first year of lifeAsymmetric IUGRType II

Late onset growth restrictionHead SparingPotentially reversibleAssociated with decreased cell sizeInfants demonstrate more catch-up growth than symmetric IUGR in first year of lifeTypes of SGA / IUGR

DIAGNOSIS

Decreased subcutaneous fat with soft tissue, desquamated skin, meconium stainedWidened cranial sutures with large fontanellesThin umbilical cordSkin and sole creases more mature than GAalert-looking and jitteryCongenital malformationsStigmata of congenital infections

SPECIFIC PROBLEMS

Intrauterine : sudden fetal death, fetal distress during laborAt birth: birth asphyxia, MAS often complicated by pneumotorax

Neonatal period # Congenital malformations: There is 20 x increased incidence of congenital malformation in SGA babies compared with their birthweight peers # Infections: There is 7 x increased incidence of infections. The intrauterine infections may be the cause of the growth retardation, but SGA babies are also more likely to acquire a nursery infections

# Hypocalcaemia: the increased incidence of hypocalcaemia relates to the birth asphyxia & not to SGA infant # Hypoglycaemia : due to poor body reserves of brown fat & glycogen. # Polycythaemia :especially when there has been prolonged intrauterine hypoxia resulting in elevated levels of erythropoertin

# Thermal instability: maintenance of body temperature is a problem to the SGA infant but less so than for preterm infant. This probably related to the large surface area to body weight ratio. # Respiratory Distress: may due to MAS, Polycythaemia, massive pulmonary haemorrage or pneumonia but not usually due to RDS

Infancy and childhood Growth and development : in the neonatal period, the infant loses little weight & begins to gain weight rapidly after birth. However, this growth spurts is often not maintained & permanent deficit in somatic growth may persist into childhood.

MANAGEMENT

If IUGR suspected: monitoring of fetal & uteroplacental function will be necessary with test such as 24 hr urinary oestriol, serial biparietal diameters, stress & non stress challenge test & L/S ratio of amniotic fluid prior to early delivery

A careful decision: best methode of & time of delivery will need to be made.

The baby should be transferred to special care nursery for careful observation for signs of RDS, hypoglycaemia, & temperature instability.

The SGA infants should commence feeds at 2 hr of age, if possible & initially feeding should be every 2 hr with dextrostix estimated of blood glucose before each feed.

The first feed should be D10% & then followed by full strength formula.

The infant should receive 60 ml/kg on day 1 & increased to 200 ml/kg by day 7.If the infant develops hypoglycaemia (dextrostix < 2,2 mmol/l or < 40 mg/dl) dispite early feeding D10% is given by uninterrupted intravenous infusion, in the additional to the oral feed.

A cappilary haematrocit at 4 to 6 hr of age should always be performed if > 70%, venous haematrocrit is indicated. If venous Ht > 70 or if the baby has symptoms polycytemia dilutional exchange transfusion with FFP is indicated

haematrocrit is indicated. If venous Ht > 70 or if the baby has symptoms polycytemia dilutional exchange be performed if > 70%, venous The infant should receive 60 ml/kg on day 1 & increased to 200 ml/kg by day 7.If the infant develops hypoglycaemia (dextrostix < 2,2 mmol/l or < 40 mg/dl) dispite early feeding D10% is given by uninterrupted intravenous infusion, in the additional to the oral feed.

A cappilary haematrocit at 4 to 6 hr of age should always transfusion with FFP is indicated

Application of the international foetal growth reference curve will vary according to its specific clinical and public health uses or purposes. Criteria for diagnosis of foetal growth restriction (e.g., SGA) should be related to evidence of increased risk for perinatal mortality and/or other indices of adverse outcomes. The new reference should provide percentiles [(e.g., 3rd, 5th, 10th, 15th, 25th, 50th (median), 75th, 85th, 90th, 95th, and 97th)] as well as z-scores [(e.g., -3, -2, -1, 0 (mean), 1, 2, and 3 SD)], so that health planners and practitioners can use the most appropriate cut off based on local circumstances.Proportionality at birth may be related to adverse outcomes. Thus there is a need to develop reference data for birth length and head circumference in relation to GA, and for birth weight in relation to birth length. Because the concepts of 'wasting' and 'stunting' have proven useful for categorizing undernourished infants and older children, an attempt should be made to quantify the mortality and morbidity risks associated with 'wasted' and 'stunted' newborns and to develop indicators for their classification. IUGR can be difficult to diagnose and in many cases doctors are not able to make an exact diagnosis until the baby is born. A mother who has had a growth restricted baby is at risk of having another during a later pregnancy. Such mothers are closely monitored during pregnancy. The length in weeks of the pregnancy must be carefully determined so that the doctor will know if development and weight gain are appropriate. Checking the mother's weight and abdomen measurements can help diagnose cases when there are no other risk factors present. Measuring the girth of the abdomen is often used as a tool for diagnosing IUGR. During pregnancy, the healthcare provider will use a tape measure to record the height of the upper portion of the uterus (the uterine fundal height). As the pregnancy continues and the baby grows, the uterus stretches upward in the direction of the mother's head. Between 18 and 30 weeks of gestation, the uterine fundal height (in cm.) equals the weeks of gestation. If the uterine fundal height is more than 2-3 cm below normal, then IUGR is suspected. Ultrasound is used to evaluate the growth of the baby. Usually, IUGR is diagnosed after week 32 of pregnancy. This is during the phase of rapid growth when the baby should be gaining more weight. IUGR caused by genetic factors or infection may sometimes be detected earlier.