General Introduction Of Neonate

General introduction of neonate

Falin Xu M.D Ph.D Department of pediatrics The third affiliated hospital of Zhengzhou University

Newborn infants      

Introduction Definitions and classifications Characteristic features of newborn Minor clinical problems Major problems in preterm infants Routine care of neonate

Introduction (1)   

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Neonate and Neonatology Newborn period encompasses the first 4 weeks of extrauterine life. Newborn period is an important link in the chain of events from conception to adulthood. Fetal and neonatal life are best regarded as a continuum.

Introduction(2)  

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The morbidity and mortality rates in newborn infants are high. Nearly 65 percent of infant deaths occur in the newborn period.It is highest during the first 24 hour of life. In united states ,of all deaths occuring in the first year,two thirds are in neonatal period.

Introduction(3) Perinatal period 

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extends from 28th week of gestation to 7th day after birth. extends from 20th week of gestation to 28th day after birth. extends from 28th week of gestation to 28th day after birth. extends from embryogeny to 7th day after birth.

Introduction(4)   

According to WHO the Perinatal mortality rate in developed countries has fallen. In India ,the current neonatal mortality rate is 47per 1000 live births. In 1996,the infant mortality rates were lowest in Singapore and Japan (3.8‰),in USA is 7.3 ‰ and highest in developing countries(30~150 ‰).

The important causes of neonatal death 

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Low birth weight: is the single most important determinant of neonatal deaths. Over 80~90% neonatal deaths occur among LBW infants. Infection Birth asphyxia and prematurity Congenital malformations

Definitions and classifications 

Definitions 1)neonate 2)neonatal period 3)live-born 4)still-birth 5)perinatal mortality rate 6)neotanal mortality rate

definitions Term

Definition

neonate

The infant from birth to under four weeks (<28 days)

Neonatal period

First month of life

Live-born

A neonate shows any evidence od life such as breathing ,heart beat,

Still-birth

Afetus born after 24weeks of gestation who shows no signs of life after delivery

Perinatal mortality rate

Still births and deaths within the first 6 days per 1000 live and still births

Neonatal mortality rate

Deaths of liveborn infants during the first 28 days of age per1000 live births

Classifications-1 

According to GA (gestational age )

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gestational age:from the first day of the last menstruation to delivery 1)term baby:a baby born between 37 and 42 weeks gestation irrespective of the birth weight 2)preterm baby: a baby born at any time before 37 weeks gestation irrespective of the birth weight 3)posterm baby:a baby born after 42 weeks gestation irrespective of the birth weight

Classifications-2 

According to BW (birth weight)

1)LBW (low birth weight) baby VLBW (very low birth weight) baby ELBW (extremely low birth weight) baby  2)NBW (normal birth weight) baby  3)macrosomia baby

Classifications-3 

According to the relation between GA and BW

1)AGA (appropriate for gestational age)baby 2)SGA(small for gestational age)baby 3)LGA(large for gestational age)baby 

Classifications-4 

According to the weeks after birth 1)early newborn baby: first week of life 2)late newborn baby: a baby extends from 7th to 28th day after birth

High risk infants      

Demographic social factors Past medical history Prior pregnancy Present pregnancy Labor ang dilivery Neonate

Definition for size and gestational age Term

Definition

preterm

Gestation<37completed weeks

Post-term

Gestation>42 completed weeks

term

Gestation between 37and 42 weeks

Low birth weight

<2500g

Very low birth weight

<1500g

Extremely lowbirth eight

<1000g

Small for gestational age Birthweight<10th centile for gestational age Large for gestational age

Birthweight >90th centile for gestational age

the characteristic features of newborn

Appearance feature 

1

Appearance fe

ature

term

preterm

skin

Pint,fatty skin

Deep red,smooth,thin skin,edema

head

Big head (1/4 of height) less lanugo

Bigger head (1/3 of height) More lanugo

skull

Hard,ears standing

Soft,ears floppy

nail

Beyond fingertips

Not Beyond fingertips

Size and growth    

The average weight of term infant in the UK is about 3500g.in India ,it is about 2800g. boys weigh approximately 250g more than girls. In china it is about 3000g. In the first month,average weight gain per week is about 200g.

Size and growth 

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During the first 3~5 days , up to 10% of birthweight is lost, this is regained by 7~10days.it is physiologically. The average height of neonate in china is about 50cm. at 1year old is about 75cm.

skin 

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The neonatal skin is thin and immature. it is easily injured and infected. Combined with the large surface area per unit of body weight ,newborn is prone to develop hypothermia,especially preterm baby. Skin is easily injured and infected.

Head   

The neotatal head is bigger than adult relatively. The average occipitofrontal head circumference is 33~34cm. Two fontanelles are present.the anterior fontanel closes between 12 and 18 months of age,the posterior fontanel closes by 6~8weeks of age.

Respiratory system   

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Fetus has not effective pulmonary respiratory. After birth and cry,the lung expanded,the infant only can make effective respiratory. Pulmonary surfactant(PS) lines the air-fluid interface of the alveolus and reduces the surface tension thereby facilitating lung expansion. The preterm baby is often short of PS,so RDS usually happens in preterm infants.

Respiratory system  

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Neonate breathes mainly with the diaphragm. Respiratory rate is variable and normally ranges between 30~50 breaths per minute. a rate consistently over 60 brearhs per minute usually indicates pulmonary, cardiac, or metabolic disease. Periodic breath and apnea: usually occur in preterm infants.

Cardiovascular system 

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In the fetal circulation,the rightsided(pulmonary)pressure exceeds the left-sided(systemic)pressure. Blood flows from right to left through the foramen ovale and ductus arteriosus.

Cardiovascular system Changes of circulation after birth : Left-sided pressure rises with clamping of umbilical vessels.  right -sided pressure falls as the lungs expand and the rising Po2. 

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The foramen ovale and ductus arteriosus close functionally shortly after birth.

Cardiovascular system 

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The neonatal heart beat rate ranges between 90~160 per min. preterm infants whose heart beat rate is usually 140~160 per min. The average blood pressure of neonate is about 70/50mmHg. Bp will increase with growth.

Gastrointestinal system 

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At term ,the secretory and absorbing surfaces are well-developed. The capacity of stomach is relatively small,it is about 30~50ml.neonate often vomit milk. The liver is usually palpable,as much as 2cm below the rib margin.

Gastrointestinal system 

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Meconium is black,thick and viscid.it usually passed within 24hours in a large proportion of neonates. delayed beyond 24 hours is considered abnormal. with normal feeding ,changing stools replace meconium on 3 or 4 days. Infant is ready to feed within the first hour after birth.exclusive breast feeding is natural normal nutrition.feeding neonate whenever he needs.

Gastrointestinal system 

Immaturity of the live enzymes responsible for conjugation of bilirubin is responsible for the neonatal jaundice.

Genitourinary system 

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Urine production is occuring during the second half of gestation and accounts for much of the amniotic fluid. Urine is usually passed during or shortly after birth. About 94% of neonate pass urine by 24 hours after birth,delayed beyond 48 hours is considered abnormal.

Genitourinary system 

Late metabolic acdosis

Haematopoietic system  

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The newborn’s mean hemoglobin is about 170g/L,ranges from 140~200g/L. RBC contains fetal hemoglobin(HbF) which transports O2 at lower pressure than adult hemoglobin(HbA). WBC is also higher ,is about 15~20 *109/L after birth and reduces several days later. The blood capacity is about 85~110ml/kg.

Haematopoietic system 

Physiologic anemia

Immune system     

Immune system is also immature. The cellular and humoral immune responses are limited. The infant depends on maternal IgG antibody which have crossed the placenta. IgA is found in breast milk. Becouse of deficiency of IgM and IgA antibody ,newborn is easily infected in respiratoral and gestrointestinal system.

Central nervous system     

The brain is relatively bigger. CNS is immature at birth. Newborn infants sleep for a total of 16~20 hours each day. A number of primitive neonatal reflexes can be elicited in healthy term neonate. These reflexes usually disappear after several months.

Central nervous system 

Primitive reflexes includes: Rooting reflex Sucking reflex Grasp reflex Moro’s reflex

Minor clinical problems 

These usually are observed in normal infants during the first week of life. Milia Breast engorgement Vaginal bleeding Physiological jaundice Caput succedaneum Cephal hematoma

Major problems in preterm infants Majorproblems in preterminfants system

Problem

Respiratorysystem

Surfactantdeficiency Apnoeicattacks

Cardiovascularsystem

Hypotension Patentductusarteriosus

Tem peraturecontrol

hypotherm ia

Gastrointestinal tract

Nutrition Reflux Jaundice Necrotizingenterocolitis Intracranial hem orrhage/ischaem ia

Nervoussystem Im m unesystem

infection

m etabolism

Hypoglycaem ia osteopenia

Routine care of neonate Care of the umbilical stump Umbilical cord is cut about 2~3cm.it is left dry and normally fall off in 5 to 10 days.  Maintaining body temperature Brown fat Neutral thermal environment 

Routine care of neonate 

Nutrition and fluids The newborn infants require fluids 100~150ml/kg/d Calorie requirement is about 110~130kcal/kg/d

Routine care of neonate Avoiding infection Washing hand before and after handling the baby. Antibiotic can be used in infected babies.  Immunotherapy HBV-vaccine BCG-vaccine 