Small for Dates Flashcards
What are the 2 main groups of small babies?
- Pre-term delivery.
* Small for gestational age.
What are the 2 subcategories for SGA babies?
- Intra-uterine growth retardation (IUGR). (placenta isn’t working properly and baby isn’t growing well)
- Constitutionally small.
What is pre-term birth defined as?
Delivery between 24 and 36+6 weeks.
What is the prevalence of pre-term babies?
Approx 6-7%.
Globally – 15million babies per year.
What are the survival rates like at i)24 weeks ii) 27 weeks iii) 32 weeks?
i) ~20-30%.
ii) 80%.
iii) >95%.
List some causes of pre-term birth.
- Infection
- ‘Over distension’
- Vascular
- Intercurrent illness
- Cervical insufficiency (get painless dilatation of cervix, rupture of membranes and loss of the pregnancy)
- Idiopathic
List some intercurrent illnesses which may lead to pre-term birth.
- Pyelonephritis / UTI
- Appendicitis
- Pneumonia
List risk factors associated with pre-term birth.
- Previous PTL (20% risk X1; 40% X2))
- Multiple (50% risk)
- Uterine anomalies
- Age (teenagers)
- Parity (=0 or >5)
- Ethnicity
- Poor socio-economic status
- Smoking
- Drugs (especially cocaine)
- Low BMI (<20)
What is the biggest cause of pre-term birth (40%)?
Unknown
25% of pre-term births are planned caesarean sections. Why might one of these be required?
- Severe pre-eclampsia.
- Kidney disease.
- Poor foetal development.
What are the other 25% of pre-term births caused by?
Emergency events – placental abruption, infection, eclampsia.
What causes 20% of pre-term births?
Premature rupture of membranes.
What do steroids help with in the context of pre-term birth?
Maturation of type 2 pneumocytes in the lungs.
What improves time form ruptured membranes to delivery?
Erythromycin.
Describe placenta abruption.
Hard, ‘woody’ abdomen and uterus, with contractions occurring one after the other
What is small for gestational age defined as?
An infant with birthweight that is less than the 10th centile for gestation corrected for maternal weight, fetal sex and birth order.
If the 10th centile is used as the cut off for SGA, 50% . .
Will be fine, just small, while the other half will probably be running into problems
What 3 factors can poor growth be attributed to?
1 – Maternal.
2 – Foetal.
3 – Placental.
List maternal factors which may contribute to poor growth.
- Lifestyle - smoking, alcohol, drugs (esp cocaine)
- Height and weight (low/high BMI)
- Age.
- Maternal disease e.g. hypertension, diabetes (assoc. w/ macrosomia, but can sometimes cause vascular problems in the placenta and result in IUGR).
What foetal factors may contribute to poor growth?
- Infection e.g. rubella, CMV, toxoplasma.
- Congenital anomalies e.g. absent kidneys.
- Chromosomal abnormalities e.g. Down’s syndrome.
What placental factors may contribute to poor growth?
- Infarcts.
- Abruption.
- Often secondary to hypertension.
If a baby is <10th centile, it can be categories as either ….
- SGA
2. IUGR
Late onset IUGR – tends to be associated with a normal head, and small abdomen.
TRUE
IUGR can be either ….
Symmetrical
OR
Asymmetrical
Antenatally, or in labour, what is there a risk of?
Hypoxia +/or death
What are the potential post-natal consequences of being growth restricted?
- Hypoglycaemia
- Effects of asphyxia
- Hypothermia
- Polycythaemia
- Hyperbilirubinaemia
- Abnormal neurodevelopment
What are the clinical features of poor growth?
- Predisposing factors.
- Fundal height less than expected.
- Reduced liquor.
- Reduced fetal movements.
What should fundal-symphyseal height be roughly equal to?
Number of weeks gestation +/-2cm.
What are the components of an assessment of foetal wellbeing?
- Assessment of growth.
- Cardiotocography.
- Biophysical assessment.
- Doppler ultrasound.
On US, what should be measured when assessing growth?
Head circumference.
Abdominal circumference.
Femur length.
Outline the 2 parts of CTG.
1 – picks up the fetal heart rate with doppler US.
2 – picks up contractions.
What is the normal foetal heart rate?
110-160 bpm
What can loss of baseline variability on a CTG indicate?
Greater possibility of asphyxia
Longer lag time of decelerations on CTG ….
More serious foetal asphyxia
What does assessment of foetal wellbeing involve and consider?
- Ultrasound assessment.
- Considers:
- movement.
- tone.
- foetal breathing movements.
- liquor volume.
How is assessment of foetal wellbeing scored?
Out of 10:
- 8-10 = satisfactory.
- 4-6 = repeat.
- 0-2 = deliver.
What does the umbilical arterial doppler use?
US
What does the umbilical arterial doppler measure during foetal assessment?
Placenta resistance to flow
What vessels run through the umbilical cord?
2 little arteries and 1 big vein (looks like a smiley face).
What does a doppler trace look like?
Toblerone, with lots of ‘chocolate’ between the chunks.
What happens to blood flow if placenta isn’t working or the baby is anaemic? Why?
You get faster blood flow in the brain
The blood is being diverted to the more essential organs
Describe the ductus venosus doppler.
From the umbilical vein into the heart.
Little wave you see is a reflection of cardiac contractility.
What is the danger of delivery which is too early?
Iatrogenic prematurity
What is the danger of delivering a baby too late?
Perinatal asphyxia/IUFD (intra-uterine foetal demise).
