Small for Dates Pregnancy Flashcards
What may cause a baby to be small for dates?
- pre term delivery
- small for gestational age
- IUGR/FGR
- Constitutionally small
What is preterm delivery?
delivery before 37 weeks gestation
- extreme preterm: 24-27+6 weeks
- very preterm: 28-31+ 6 weeks
- moderate to late preterm: 32- 36+6 weeks
When is viability defined in the UK?
24 weeks
when does your baby have a 40% chance of survival?
24 weeks
What is the aetiology of preterm birth?
- infection
- over distension
- multiple pregnancy
- polyhydramnios
- vascular
- placental abruption
- intercurrent illness
- pyelonephritis/UTI
- appendicitis
- pneumonia
- cervical incompetence
- idiopathic
What are the risk factors for preterm birth?
- Previous PTL (20% risk x1, 40% risk x2)
- multiple pregnancy (50%)
- uterine anomalies
- age (teenager)
- parity 0 or >5
- ethnicity
- poor socio-economic status
- smoking
- drugs (especially cocaine)
- low BMI <20
what percentage of preterm births are planned?
25%
what percentage of preterm births are due to premature rupture of membranes?
20%
what percentage of preterm births are due to emergency event?
25%
What is IUGR/FGR?
failure to achieve growth potential
What is low birth weight?
Birth weight below 2.5kg regardless of gestation
SGA fetus is defined as an estimated fetal weight or abdominal circumference meaurement below the __th centile.
SGA fetus is defined as an estimated fetal weight or abdominal circumference meaurement below the 10th centile.
What are the two broad divisions of IUGR and why do they occur?
Symmetrical- may point to a chromosomal abnormality or in utero infection
Asymmetrical- placental reasons, baby is diverting blood to head to protect brain growth over other less vital organs.
How do we identify a SGA foetus?
Antenatal risk factors
Screening during antenatal care
A single major risk factor of SGA means that we should be formally measuring and monitoring fetal growth by means of ultrasound to estimate fetal size from 26-28 weeks, and at regular intervals until approximately __ weeks. In practice this usually means minimum scans at __, __ and __ weeksgestation. This is what we usually mean if you here us say “serial growth scans”.
A single major risk factor means that we should be formally measuring and monitoring fetal growth by means of ultrasound to estimate fetal size from 26-28 weeks, and at regular intervals until approximately 36 weeks. In practice this usually means minimum scans at 28, 32 and 36 weeksgestation. This is what we usually mean if you here us say “serial growth scans”.
3 minor risk factors for SGA at a minimum requires a growth scan at __ weeks and if there is an abnormal uterine artery doppler measurement at __ weeks then they would be monitored as if they had a major risk factor.
3 minor risk factors at a minimum requires a growth scan at 34 weeks and if there is an abnormal uterine artery doppler measurement at 20 weeks then they would be monitored as if they had a major risk factor.
When should all women get symphysial fundal height measured?
24 weeks
What measurements are taken to diagnose SGA?
- Measurement of fetal AC
- Combine with head circumference +/- femur length to give EFW
- Additional information: liquor volume or amniotic fluid index and Dopplers
What is visualised in an ultrasound image being used to measure AC?
Stomach bubble, single rib, c-shaped umbilical vein.
What do customised growth charts take into account?
maternal parity, BMI, ethnicity
What are the maternal factors of SGA?
- lifestyle
- smoking
- alcohol
- drugs
- height and weight
- age
- maternal disease e.g. hypertension
When do all women have a UAD?
at 20 week scan
Pregnancy should be a ___ resistance state and the uterine arteries should become a low resistance vessel in the ___ trimester with forward flow to the placenta even in _______. Measurement of the flow through these vessels may show resistance, if resistance is found in both uterine arteries this woman is at risk of ___ and _________ disease in pregnancy. This is most likely due to abnormal ________, so failure of the _____ artery invasion.
Pregnancy should be a low resistance state and the uterine arteries should become a low resistance vessel in the 2nd trimester with forward flow to the placenta even in diastole. Measurement of the flow through these vessels may show resistance, if resistance is found in both uterine arteries this woman is at risk of SGA and hypertensive disease in pregnancy. This is most likely due to abnormal placentation, so failure of the spiral artery invasion.
What placental factors contribute to SGA?
- infarcts
- abruption
- often secondary to hypertension
What foetal factors contribute to SGA?
- Infection e.g. rubella, CMV, toxoplasma
- congenital anomalies e.g. absent kidneys
- chromosomal abnormalities e.g. down’s syndrome
What are antenatal/labour complications of SGA?
Risk of hypoxia and or death
What are the postnatal complications of SGA?
- hypoglycaemia
- effects of asphyxia
- hypothermia
- polycythaemia
- hyperbilirubinaemia
- abnormal neurodevelopment
What clinical features suggest poor growth?
- Predisposing factors
- Fundal height less than expected
- Reduced liquor
- Reduced fetal movements
How is foetal wellbeing assessed?
- assessment of growth
- cardiotocography
- biophysical assessment
- doppler ultrasound
What is a biophysical profile?
- ultrasound assessment
- considers
- movement
- tone
- fetal breathing movements
- liquor volume
What is the primary tool for monitoring the SGA and helping to time delivery?
UAD
What are the indications for early delivery of SGA baby?
- considering earlier delivery by caesarean section:
- Growth becomes static (IOL may be appropriate)
- Abnormal umbilical artery Doppler
- Normal umbilical artery Doppler with abnormal MCA between 32 and 37 weeks
- Abnormal umbilical artery Doppler with abnormal ductus venosus Doppler between 24-32 weeks
babies who are identified as SGA will usually be delivered by __ weeks and that’s even if evrything else looks ok-so growing although small with normal dopplers and liquor volume.
babies who are identified as SGA will usually be delivered by 37 weeks and that’s even if evrything else looks ok-so growing although small with normal dopplers and liquor volume.
In cases where an earlier delivery is planned what medications may be given?
- steroids- to promote foetal lung maturity (if delivery planned before 36 weeks)
- magnesium sulphate- provides some foetal neuroprotection against cerebral palsy (if delivery planned before 32 weeks)
The management and timing of delivery of the SGA infant is a balance between the risks of _______ and the potential of _______ in utero or ____ _____.
The management and timing of delivery of the SGA infant is a balance between the risks of prematurity and the potential of hypoxia in utero or still birth.
