Size At Birth Flashcards
What is classified as low birth weight?
Less than 2.5kg
What percentage of babies in the UK are of low birthweight?
7%
However, they account for 70% of neonatal deaths
Babies with a birth weight below the 10th centile for their gestational age are called..,
Small for gestational age or small-for-dates
Are the majority of babies born small for gestational age, normal?
Yes they are normal but small
The incidence of congenital abnormalities and neonatal problems is higher in those who’s birthweight falls below the …
Second centile - approx 2 standard deviations below the mean (some authorities restrict the term small for gestation age to this group)
An infants birthweight may be low because of preterm birth or because the infant is both preterm and small for gestational age. True or false?
True
Small for gestational age infants may have grown normally but are small, or they may have experienced what?
Inter uterine growth restriction (IUGR)
What is IUGR?
When the baby has failed to reach their full genetically determined growth potential and appear thin and malnourished
Can babies above the 10th centile be malnourished?
Yes e.g a fetus may be growing along the 80th centile and develop growth failure and weight then falls to the 20th centile
Growth restriction in fetus and infant has been classified as…
Symmetrical or asymmetrical
Is symmetrical or asymmetrical growth restriction more common?
Asymmetrical
Describe asymmetrical growth restriction
The weight or abdominal circumference lies on a lower centile compared to that of the head
Asymmetrical growth restriction occurs when..
The placenta fails to provide adequate nutrition late in the pregnancy but brain growth is relatively spared at the expense of liver glycogen and fat
Asymmetrical growth restriction is associated with uteroplacental dysfunction secondary to..
Maternal pre eclampsia
Multiple pregnancies
Maternal smoking
Or can be idiopathic
Do those with asymmetrical growth restriction put on weight after birth?
Yes rapidly
What is asymmetrical growth restriction associated with later in life?
Increased obesity risk and type 2 DM later in life
Describe symmetrical growth restriction
The head circumference is equally reduced
What does symmetrical growth restriction suggest?
A prolonged period of poor intrauterine growth starting in early pregnancy (or that gestational age in incorrect)
What is symmetrical growth restriction due to?
Usually small but normal fetus
May be due to a fetal chromosome disorder or syndrome, congenital infection, maternal drug and alcohol abuse, maternal chronic medical condition or malnutrition
Are those with symmetrical growth restriction more or less likely to remain small permanently?
More likely
In practice can the distinction between asymmetrical and symmetrical growth restriction be made?
No
The fetus with IUGR is at risk from …
Intrauterine hypoxia and unexplained uterine death
Asphyxia during labour and delivery
Progressive uteroplacental failure results in..
Reduced growth in femur length and abdominal circumference
Oligohydraminos from reduced fetal urine production
Abnormal umbilical artery Doppler waveforms
Redistribution of blood flow in fetus - increased to brain, reduced to GI tract, liver, skin and kidneys
Abnormal ductus venosus Doppler waveform from cardiac dysfunction
Reduced fetal breathing and movements
Abnormal fetal heart rate trace
After birth, growth restricted infants are liable to…
Hypothermia due to their relatively large surface area (especially head)
Hypoglycaemia from poor fat and glycogen stores
Hypocalcaemia
Polycythemia
Large for gestational age infants are those above what centile for their gestation?
90th
What causes infants who are large for gestation age ?
Most are normal
Mother has DM type 1 or gestational diabetes
Congenital syndromes e.g Beckwith-Wiedemann syndrome
What problems are the associated with being large for gestational age?
Birth trauma - especially from shoulder dystocia at delivery
Birth asphyxia from difficult delivery
Hypoglycaemia due to hyperinsulinism
Polycythemia
Breathing difficulty from enlarged tongue in Beckwith-Weidemann syndrome
