Small for Dates/Pre-term birth

Question 1

What is a pre-term birth?

Answer 1

Delivery between 24 and 36+6 weeks

Question 2

What are the survival rates of pre-term births?

Answer 2

24 weeks approx 20-30%
27 weeks 80%
32 weeks >95%

Question 3

What is the prevalence of pre-term births?

Answer 3

6-7%

Question 4

What are the possible causes of a pre-term birth?

Answer 4

Infection
Over distension: multiple, polyhydramnios
Vascular: placental abruption
Intercurrent illness: pyelonephritis/UTI, appendicitis, pneumonia
Cervical incompetence
Idiopathic

Question 5

What are some of the RFs/associations of pre-term birth?

Answer 5

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)

Question 6

Why do pre-term births occur?

Answer 6

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

Question 7

What is small for gestational age (SGA)?

Answer 7

Infant with a birthweight that is less than 10th centile for gestation corrected for maternal height, weight, fetal sex and birth order

Question 8

What maternal factors can cause poor growth in IUGR?

Answer 8

Lifestyle: smoking, alcohol, drugs
Height and weight
Age
Maternal disease e.g. HT

Question 9

If a baby is under the 10th centile, what categories can it be described under?

Answer 9

SGA

Intra-uterine growth restriction (IUGR)

Question 10

What fetal factors can cause poor growth in IUGR?

Answer 10

Infection e.g. rubella, CMV, toxoplasma
Congenital anomalies e.g. absent kidneys
Chromosomal abnormalities e.g. Down’s syndrome

Question 11

What placental factors can cause poor growth in IUGR?

Answer 11

Infarcts
Abruption
Often 2’ to HT

Question 12

How can IUGR be classified?

Answer 12

Symmetrical

Asymmetrical

Question 13

What are antenatal/in labour consequences of being growth restricted?

Answer 13

Risk of hypoxia and/or death

Question 14

What are some post natal consequences of being growth restricted?

Answer 14

Hypoglycaemia
Effects of asphyxia
Hypothermia
Polycythaemia
Hyperbilirubinaemia
Abnormal neurodevelopment

Question 15

What clinical features can be seen in poor growth?

Answer 15

Predisposing factors
Fundal height less than expected
Reduced liquor
Reduced fetal movements

Question 16

Overall what is done to assess fetal wellbeing?

Answer 16

Assessment of growth
Cardiotocography
Biophysical assessment
Doppler US

Question 17

What is defined as a loss of baseline variability?

Answer 17

Baseline FHR variability of less than 5bpm

Question 18

What may cause a loss of baseline variability?

Answer 18

Sedative or analgesic drugs used in labour

Question 19

In general the less baseline variability there is means that the possibility of asphyxia is increased or decreased?

Answer 19

Increased

Question 20

What are late decelerations?

Answer 20

Any deceleration whose lowest point is past the peak of the contraction (decelerations with lag time)

Question 21

What does a longer lag time result in?

Answer 21

An increased fetal asphyxia

Question 22

What is included in a biophysical profile?

Answer 22

US assessment
Looks at: movement, tone, fetal breathing movements, liquor volume
Scored out of 10: 8-10 satisfactory, 4-6 repeat, 0-2 deliver

Question 23

What does an umbilical arterial Doppler measure?

Answer 23

Placental resistance to flow

Question 24

What is the risk of delivering too early?

Answer 24

Iatrogenic prematurity

Question 25

What is the risk of delivering too late?

Answer 25

Perinatal asphyxia/IUFD