Small for Dates Flashcards

1
Q

What can cause a baby to be small for its date?

A
  • Pre term delivery
  • Intra uterine growth restriction (IUGR)
  • Constitutionally small
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2
Q

A preterm birth is before what gestational age?

A
  • Delivery before 37 weeks
  • Extreme preterm: 24 – 27+6 weeks
  • Very preterm: 28 – 31+6 weeks
  • Moderate to late preterm: 32 – 36+6 weeks
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3
Q

What is the difference in survival when babies are born very preterm?

A

23 weeks = 19%
Whereas
26 weeks = 77%

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4
Q

What conditions may cause a preterm birth?

A
  • Infection - Pyelonephritis / UTI/ Appendicitis/ Pneumonia
  • ‘Over distension’ => Multiple Preg/Polyhydramnios
  • Vascular => Placental abruption
  • Cervical incompetence
  • Idiopathic
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5
Q

What factors increase the risk of a preterm birth?

A
  • Previous pre-term labour
  • Multiple
  • Uterine anomalies
  • Age (teenagers)
  • Parity (=0 or >5)
  • Ethnicity
  • Poor socio-economic status
  • Smoking
  • Drugs (especially cocaine)
  • Low BMI (<20)
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6
Q

What can cause a pre-term labour?

A
  • Planned caesarean section (pre-eclampsia, kidney disease or poor fetal development)
  • Premature rupture of membranes
  • Emergency (placental abruption, infection, eclampsia)
  • Idiopathic
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7
Q

What does it mean if a baby is defined as “Small for Gestational Age”?

A

Estimated foetal weight (EFW) or Abdominal Circumference below the 10th centile

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8
Q

What is meant by the terms Intra-uterine growth restriction (IUGR) and low birth weight (LBW)?

A

IUGR = Failure to achieve growth potential

LBW = birth weight below 2.5 kg (regardless of gestation)

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9
Q

Intra-uterine growth restriction can be symmetrical or asymmetrical. Explain what this means and what is most likely to cause each.

A

Symmetrical = all parts of baby’s body are proportionately small
- usually caused by chromosomal problem

Asymmetrical = head normal, but abdomen is small => disproportionate to each other
- usually caused by placental supply problems => foetus directs all blood to head to keep brain perfused

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10
Q

Give some examples of major and minor antenatal risk factors for small babies?

A

MAJOR

  • BMI>40
  • Smoking >11 cigarettes /day
  • Other medical conditions - HT, Diabetes, renal disease, antiphospholipid

MINOR

  • Maternal age >35 years
  • IVF
  • Low BMI <20
  • Smoker 1-10 cigarettes/day
  • Low fruit pre-pregnancy
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11
Q

How do we screen for small babies antenatally?

A
  • Measurement of symphysial-fundal height from 24 weeks

- Growth scan if measurement below 10th centile on customised chart

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12
Q

HOw can we diagnose a baby that is small for gestational age?

A
  • Measurement of fetal abdominal circumference
  • Combine with head circumference +/- femur length to give Estimated Foetal Weight (EFW)
  • liquor volume or amniotic fluid index can also be used to see if baby is producing enough fluid
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13
Q

How is EFW/AC Measurement standardised? WHat is seen on every womans scan to calculate this?

A

Scan till we can see:

  • stomach gas bubble
  • C shaped umbilical vein
  • One rib

ALL in the same snapshot on US

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14
Q

What do customised charts take into account that population charts do not?

A
  • BMI
  • Parity of mother
  • Ethnicity
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15
Q

What maternal factors can cause a baby to be Small for gestational age (SGA)?

A
  • Lifestyle (smoking, alcohol, drugs)
  • Height and weight
  • Age
  • Maternal disease e.g. hypertension
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16
Q

What are uterine artery dopplers used to measure?

A

Resistance in uterine arteries
- “notch” indicates high resistance in vessels
=> harder for blood to reach baby
=> harder for baby to grow

17
Q

What placental factors can cause a baby to be small for their gestational age?

A
  • Infarcts
  • Abruption

Often secondary to hypertension

18
Q

What are the potential foetal causes of a baby being small for their gestation?

A
  • Infection e.g. rubella, CMV, toxoplasma
  • Congenital anomalies e.g. absent kidneys
  • Chromosomal abnormalities e.g. Down’s syndrome
19
Q

What are the consequences of IUGR antenatally or when the mother is in labour?

A
  • hypoxia and or death
20
Q

What are the consequences of IUGR postnatally for the baby?

A
  • Hypoglycaemia
  • Effects of asphyxia
  • Hypothermia
  • Polycythaemia
  • Hyperbilirubinaemia
  • Abnormal neurodevelopment
21
Q

HOw may poor growth be suspected clinically?

A
  • Predisposing factors
  • Fundal height less than expected
  • Reduced liquor
  • Reduced fetal movements
22
Q

What does a biophysical profile include to assess growth of the foetus?

A
US assessment that considers:
- Movement
- Tone
- Foetal breathing movements
- Liquor volume
Scores out of 10 (8-10 satisfactory)
23
Q

What is an umbilical artery doppler used for?

A

Checks placental resistance to blood flow to foetus

  • when mother is in diastole, blood flow to foetus falls
  • it should NOT stop during diastole
  • if resistance is extremely high, blood may flow BACK to the mother (Opposite direction) during diastole
24
Q

When may a small baby be delivered early by c-section?

A
  • Growth becomes static (induce labour?)
  • Abnormal umbilical artery Doppler
  • Abnormal MCA between 32 and 37 weeks
  • Abnormal umbilical artery Doppler with abnormal ductus venosus Doppler between 24-32 weeks
25
Q

What medication should be given to the mother if planning delivery?

A

Steroids

Magnesium sulphate

26
Q

Why may it be appropriate to NOT deliver a small for gestational age baby at 37 weeks (as per guidelines) if both the baby and mother are well?

A

Closer to 40 weeks = less potential for educational difficulty in later life