Small for Dates Pregnancy

Question 1

What may cause a baby to be small for dates?

Answer 1

• pre term delivery
• small for gestational age
  
  • IUGR/FGR
  • Constitutionally small

Question 2

What is preterm delivery?

Answer 2

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

Question 3

When is viability defined in the UK?

Answer 3

24 weeks

Question 4

when does your baby have a 40% chance of survival?

Answer 4

24 weeks

Question 5

What is the aetiology of preterm birth?

Answer 5

• infection
• over distension
  
  • multiple pregnancy
  • polyhydramnios
• vascular
  
  • placental abruption
• intercurrent illness
  
  • pyelonephritis/UTI
  • appendicitis
  • pneumonia
• cervical incompetence
• idiopathic

Question 6

What are the risk factors for preterm birth?

Answer 6

• 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

Question 7

what percentage of preterm births are planned?

Answer 7

25%

Question 8

what percentage of preterm births are due to premature rupture of membranes?

Answer 8

20%

Question 9

what percentage of preterm births are due to emergency event?

Answer 9

25%

Question 10

What is IUGR/FGR?

Answer 10

failure to achieve growth potential

Question 11

What is low birth weight?

Answer 11

Birth weight below 2.5kg regardless of gestation

Question 12

SGA fetus is defined as an estimated fetal weight or abdominal circumference meaurement below the __th centile.

Answer 12

SGA fetus is defined as an estimated fetal weight or abdominal circumference meaurement below the 10th centile.

Question 13

What are the two broad divisions of IUGR and why do they occur?

Answer 13

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.

Question 14

How do we identify a SGA foetus?

Answer 14

Antenatal risk factors

Screening during antenatal care

Question 15

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”.

Answer 15

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”.

Question 16

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.

Answer 16

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.

Question 17

When should all women get symphysial fundal height measured?

Answer 17

24 weeks

Question 18

What measurements are taken to diagnose SGA?

Answer 18

• Measurement of fetal AC
• Combine with head circumference +/- femur length to give EFW
• Additional information: liquor volume or amniotic fluid index and Dopplers

Question 19

What is visualised in an ultrasound image being used to measure AC?

Answer 19

Stomach bubble, single rib, c-shaped umbilical vein.

Question 20

What do customised growth charts take into account?

Answer 20

maternal parity, BMI, ethnicity

Question 21

What are the maternal factors of SGA?

Answer 21

• lifestyle
  
  • smoking
  • alcohol
  • drugs
• height and weight
• age
• maternal disease e.g. hypertension

Question 22

When do all women have a UAD?

Answer 22

at 20 week scan

Question 23

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.

Answer 23

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.

Question 24

What placental factors contribute to SGA?

Answer 24

• infarcts
• abruption
• often secondary to hypertension

Question 25

What foetal factors contribute to SGA?

Answer 25

* Infection e.g. rubella, CMV, toxoplasma * congenital anomalies e.g. absent kidneys * chromosomal abnormalities e.g. down's syndrome

Question 26

What are antenatal/labour complications of SGA?

Answer 26

Risk of hypoxia and or death

Question 27

What are the postnatal complications of SGA?

Answer 27

* hypoglycaemia * effects of asphyxia * hypothermia * polycythaemia * hyperbilirubinaemia * abnormal neurodevelopment

Question 28

What clinical features suggest poor growth?

Answer 28

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

Question 29

How is foetal wellbeing assessed?

Answer 29

* assessment of growth * cardiotocography * biophysical assessment * doppler ultrasound

Question 30

What is a biophysical profile?

Answer 30

* ultrasound assessment * considers * movement * tone * fetal breathing movements * liquor volume

Question 31

What is the primary tool for monitoring the SGA and helping to time delivery?

Answer 31

UAD

Question 32

What are the indications for early delivery of SGA baby?

Answer 32

* 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

Question 33

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.

Answer 33

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.

Question 34

In cases where an earlier delivery is planned what medications may be given?

Answer 34

* 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*)

Question 35

The management and timing of delivery of the SGA infant is a balance between the risks of _______ and the potential of _______ in utero or ____ \_\_\_\_\_.

Answer 35

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.