Problems of Low Birth weight and prematurity Flashcards
what is the median birth weight
the median UK birth weight at term (40 weeks)
what is term
40 weeks
what is the weight for
- low birth weight (LBW)
- very low birthweight (VLBW)
- Extremely low birthweight (ELBW)
Low Birthweight (LBW) = <2500g.
Very Low Birthweight (VLBW) = <1500g
Extremely Low Birthweight (ELBW) = <1000g.
what is prematurity
• Birth before 37 completed weeks of gestation
what does small for gestational age mean (SGA)
= Birth weight below the 10th/3rd centile for gestation
what is fetal growth restriction (FGR/IUGR)
failure to achieve normal rate of fetal growth (e.g from uteroplacental insufficiency or fetal infection)
what can cause Foetal growth restriction
uteroplacental insufficiency or fetal infection
why might a baby have a low birth weight
• Baby born too soon = premature.
o Note that baby can be the appropriate weight for gestation.
- Baby born too small = SGA (small for gestational age)
- Baby born too soon and too small = premature + SGA.
in order to diagnose growth restriction what do you need
- in order to diagnose growth restriction you need serial measurements of growth over the course of pregnancy
why is low birth weight important
- low birth weight is important as it indicates the chance of survival of the infant
what can happen if you are small for gestational age
- Complications of fetal growth restriction.
* Very long term health problems.
what can happen if you are premature
- Problems of prematurity- organs not ready for outside world
- Neurodevelopmental sequelae
the more premature you are…
the higher the mortality
what are the two reasons why a baby can be small for gestational age
genetics
acquired
describe the genetic and acquired reasons for a small for gestational age
Genetics • Normal small baby • Chromosomal disorders. o Edwards syndrome o Trisomy 18. • Inherited disorders.
Acquired
- Uteroplacental insufficiency - this is the most common
- congenital infection such as CMV
- smoking
- maternal chronic illness such as renal or sickle cell disease
- multiple pregnancy
What chromosomal disorders can cause you to be small for gestational age
o Edwards syndrome
o Trisomy 18.
How does utero-placental insufficiency happen
o Failure of syncytiotrophoblast invasion of the high resistance spiral arteries.
o Poor placental development with raised resistance in vascular bed.
How can you detect utero placental insufficiency
o May be detected antenatally because of poor growth.
Can be picked up using Doppler ultrasound of the uterine arteries/fetal circulation.
• Impaired placentation will impact uterine artery blood flow.
o Detects high resistance.
what happens in the hypoxic foetus
- this is when the foetus prioritises blood flow to the brain and cardiac muscle
- therefore there is a reduction in the blood going to the kidneys, gut, adrenals, liver and skin
- this causes an asymmetrical IGUR
describe what the umbilical cord is made up of
2 arteries
one vein
How can you detect a hypoxic foetus
• Can be detects by Doppler ultrasound.
o Reduced/reversed UA diastolic flow.
name some maternal chronic illnesses that can impact foetal growth
• Maternal chronic illness (renal, sickle cells disease)
o Diabetes
o Hypertension
o Coronary Heart Disease
o Stroke
o Chronic Bronchitis.
The fetal environment of these affect cellular growth/gene expression/hormonal axis.
How does CMV effect growth
Hydrocephalus and calcification of the brain.
Baby will also likely have growth restriction.
Name some problems that neonates have if they are small for gestational age
- temperature control
- polycythemia
- poor nutritional status
- hypoglycaemia
- increased risk of necrotising enterocolitis