Small for Dates/Pre-term birth Flashcards
What is a pre-term birth?
Delivery between 24 and 36+6 weeks
What are the survival rates of pre-term births?
24 weeks approx 20-30%
27 weeks 80%
32 weeks >95%
What is the prevalence of pre-term births?
6-7%
What are the possible causes of a pre-term birth?
Infection
Over distension: multiple, polyhydramnios
Vascular: placental abruption
Intercurrent illness: pyelonephritis/UTI, appendicitis, pneumonia
Cervical incompetence
Idiopathic
What are some of the RFs/associations of pre-term birth?
Previous PTL (20% x1, 40% x2) Multiple (50% risk) Uterine anomalies Age (teenagers) Parity (=0 or >5) Ethnicity Poor socio-economic status Smoking Drugs (esp cocaine) Low BMI (<20)
Why do pre-term births occur?
25% planned C section: severe pre-eclampsia, kidney disease or poor fetal development
20% premature rupture of membranes
25% emergency event: placental abruption, infection, eclampsia
40% unknown
What is small for gestational age (SGA)?
Infant with a birthweight that is less than 10th centile for gestation corrected for maternal height, weight, fetal sex and birth order
What maternal factors can cause poor growth in IUGR?
Lifestyle: smoking, alcohol, drugs
Height and weight
Age
Maternal disease e.g. HT
If a baby is under the 10th centile, what categories can it be described under?
SGA
Intra-uterine growth restriction (IUGR)
What fetal factors can cause poor growth in IUGR?
Infection e.g. rubella, CMV, toxoplasma
Congenital anomalies e.g. absent kidneys
Chromosomal abnormalities e.g. Down’s syndrome
What placental factors can cause poor growth in IUGR?
Infarcts
Abruption
Often 2’ to HT
How can IUGR be classified?
Symmetrical
Asymmetrical
What are antenatal/in labour consequences of being growth restricted?
Risk of hypoxia and/or death
What are some post natal consequences of being growth restricted?
Hypoglycaemia Effects of asphyxia Hypothermia Polycythaemia Hyperbilirubinaemia Abnormal neurodevelopment
What clinical features can be seen in poor growth?
Predisposing factors
Fundal height less than expected
Reduced liquor
Reduced fetal movements
Overall what is done to assess fetal wellbeing?
Assessment of growth
Cardiotocography
Biophysical assessment
Doppler US
What is defined as a loss of baseline variability?
Baseline FHR variability of less than 5bpm
What may cause a loss of baseline variability?
Sedative or analgesic drugs used in labour
In general the less baseline variability there is means that the possibility of asphyxia is increased or decreased?
Increased
What are late decelerations?
Any deceleration whose lowest point is past the peak of the contraction (decelerations with lag time)
What does a longer lag time result in?
An increased fetal asphyxia
What is included in a biophysical profile?
US assessment
Looks at: movement, tone, fetal breathing movements, liquor volume
Scored out of 10: 8-10 satisfactory, 4-6 repeat, 0-2 deliver
What does an umbilical arterial Doppler measure?
Placental resistance to flow
What is the risk of delivering too early?
Iatrogenic prematurity
What is the risk of delivering too late?
Perinatal asphyxia/IUFD
