Problems in Pregnancy: Small for Dates

Question 1

what is defined as a “preterm” delivery?

Answer 1

delivery before 37 weeks

extreme = 24-27+6 
very = 28-31+6 
moderate = 32-36+6

Question 2

what are the causes of preterm birth?

Answer 2

infection 
over distension (polyhydramnios)
vascular (placental abruption)
intercurrent illness (pyelonephritis, UTI, appendicitis, pneumonia)
cervical incompetence 
idiopathic

Question 3

what are the risk factors for preterm birth?

Answer 3

previous PTL
multiple birth 
uterine anomalies 
age (teenagers)
parity (=0 or >5)
ethnicity 
poor socio-economic status 
smoking 
drugs (esp cocaine)
low BMI (<20)

Question 4

what is a small for gestational age (SGA) foetus?

Answer 4

estimated foetal weight or abdominal circumference below 10th centile

*intrauterine growth restriction or foetal growth restriction

Question 5

low birth weight is classified as below what kg?

Answer 5

2.5kg (regardless of gestation)

Question 6

how is SGA screened for during antenatal care?

Answer 6

measurement of symphysial-fungal height from 24 weeks

*growth scan if single measurement below 10th centile

Question 7

how can SGA be diagnosed?

Answer 7

measurement of foetal AC

combine with head circumference +/- femur length to give EFW

*additional info = liquor volume or amniotic fluid index and dopplers

Question 8

what maternal factors could cause SGA?

Answer 8

lifestyle - smoking, alcohol, drugs
height and weight
age (>35)
maternal disease eg hypertension

Question 9

what placental factors could cause SGA?

Answer 9

infarcts
abruption
often secondary to hypertension

Question 10

what foetal factors could cause SGA?

Answer 10

infection eg rubella, CMV, toxoplasma
congenital anomalies eg absent kidneys
chromosomal abnormalities eg downs syndome

Question 11

what are the consequences of IUGR?

Answer 11

antenatal / in labour:
- hypoxia and/or death

post natal

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

Question 12

what are the clinical features of poor growth?

Answer 12

predisposing factors
fundal height less than expected
reduced liquor
reduced foetal movements

Question 13

how can foetal wellbeing be assessed?

Answer 13

assessment of growth
cardiotocography
biophysical assessment
doppler US (umbilical arterial doppler - measures placental resistance to flow)

Question 14

when should SGA babies be delivered?

Answer 14

if all well then by 37 weeks

Question 15

what are the indications for considering earlier delivery of SGA by c-section?

Answer 15

growth becomes static (IOL may be appropriate)
abnormal umbilical artery doppler
normal umbilical artery doppler with abnormal MCA between 32-37 weeks
abnormal umbilical artery doppler with abnormal ductus venosus doppler between 24-32 weeks

Question 16

what should be given in SGA babies if considering / planning delivery?

Answer 16

steroids

magnesium sulphate

Question 17

the management and timing of the delivery of SGA infant is a balance between risks of prematurity and the potential what?

Answer 17

hypoxia in utero or still birth

Question 18

what is the difference between symmetrical IUGR and asymmetrical IUGR?

Answer 18

symmetrical = both head and body small - congenital, chromosomal, intrauterine infection, environmental

asymmetrical - body small compared to normal sized heat - PET, placental causes and smoking

Question 19

what is the normal resistance of umbilical artery on doppler US?

Answer 19

normal = low resistance 
compromised = high resistance, so flow becomes absent or even reversed in diastole 

• umbilical arteries are deoxygenated and veins are oxygenated
• ductus venosus becomes pulsatile and increases its resistance
• middle cerebral artery decreases its resistance to maintain blood flow to foetal brain