Week 3 - G - Small for gestational age babies, intrauterine growth restirctions, assesing foetal wellbeing Flashcards
When looking at babies, some babies are small for gestational age What are the two different categories of baby that are small for gestational age?
Intrauterine growth restriction (IUGR) and Constitutionally small - healthy and small baby
What is considered a term birth? Preterm births can also cause the baby to be small What is considered a preterm birht?
- Term birth - anything between 37+0 weeks and before 40+6 weeks
- Preterm birth - between 24+0 weeks gestation and 36+6 weeks gestation
- Late term: Your baby is born between 41 weeks, 0 days and 41 weeks, 6 days.
- Post term: Your baby is born after 42 weeks, 0 days.
Survival rates: * 24 weeks approx 20-30% * 27 weeks 80% * 32 weeks >95%
What is the most common reason for a preterm birth?
Babies who were born early most commonly is idiopathic
INfection cause cause preterm births but usually these infections are ones which cause systemic upset Give an example
Pyelnephritis (infection of the kidneys) - can cause systemic effects leading to a premature birth
Parity of what increases the chances of pre term births?
Parity of 0 or >5 will increase the chances of a pre-term birth
Pre-term birth 25% planned caesarean section * Sever pre-eclampsia, kidney disease or poor fetal development. 20% premature rupture of membranes 25% emergency event * Placental abruption, infection, eclampsia 40% cause unknown What is premature rupture of membranes known as?
This is preterm pre-labour rupture of membranes (P-PROM) - poses a high risk for infection and antibiotics should be taken
If there is preterm - prelabour rupture of membranes, what antibitoic is the mother started on?
The mother is started on erythromycin for 10 days - this increases the time between membrane rupture and delivery - safer to deliver the baby nearer term and decreases risk of infection
If a mother develops a UTI during pregnancy, what is the treatment for each trimester?
* 1st or 2nd trimester nitrofurantoin * 3rd trimester trimethoprim * 2nd line (any trimester) cefalexin
Infant with a birthweight that is less than 10th centile for gestation corrected for maternal height, weight, fetal sex and birth order. What is this infant known as?
The infant with a birthweight less than 10th centile for gestation is known as small for gestational age (SGA)
Intrauterine growth restrictions means the infant has poor growth - can be due to maernal, feotal or placental causes What are maternal factors that may complicate to IUGR? What maternal condition can restrict growth?
Lifestyle * Alcohol * Smoking * Drugs Height and weight Age Hypertension can restrict growth
INfection and congenital abnormalities (ie one kidney) or chromsomal abnormalities of the foetus can cause IUGR Name some bacterial infections common in preterm chidlren?
CMV infection - HHV5 Rubella Toxoplasmosis Chicken pox - caused by varicella zoster virus
Placental factors such as infarct and abruption are also causes of IUGR What is palcental abruption? What may abruption and infacrtion be secondary to?
Placental abruption is where the placenta partially or completely detaches from the uterus
Both can be secondary to hypertension
Define small for gestation age again?
What does it mean for symmetrical or asymmetrical intrauterine growth restriction?
Small for gestational age - infant with a birthweight less than the 10th centile for gestation corrected maternal height, weight, foetal sex and birth order
- Symmetrical means small head and body
- Asymmetrical means one is small whislt the other is normal
What causes an asymetrical growth restriction?
This is when there is placental insufficiency meaning the babies head is usually spared but it has been starved It occurs when the placenta does not develop properly, or is damaged. It is a blood flow disorder marked by a reduction in the mother’s blood supply.
Consequences of being growth restricted They baby antenatally can become hypoxic What can hypoxia do to the brain?
Hypoxia can cause damage to the brain as it starves it of oxygen leading to cerebral palsy
What are poor clinical features for poor growth in a baby?
Reduced fundal height in comparison to gestational age Reduced liquor Reduced foetal movements - a baby who is struggling for oxygen will lie still
When measuring the fundal height, how accurate should it be for gestational age? When do foetal movements normally occur roughly?
Fundal height should be within +/- 2 weeks of gestational age Foetal movements occur around 18-20 weeks although can begin earlier or later
Assessment of foeetal wellbeing
- * Assessment of growth
- * Cardiotocography
- * Biophysical assessment
- * Doppler ultrasound
No need to carry out these assessments in a low risk delivery
On an ultrasound scan, what measurements are taken to predict foetal weight?
Foetal head circumference Femur length and Waist circumference
Left image is the babies head circumference
Right image is the waist circumference (would also measure femur length)
To assess the foetal wellbeing - cardiotoco graphy can also be carried out - this is where the foetal heart response is measured in response to uterine contractions Two belts on the tummy- one picks up fetal heart rate on ultrasound doppler. Other one- picks up contractions. To interpret a CTG you need a structured method of assessing its various characteristics. The most popular structure can be remembered using the acronym DR C BRAVADO. What does acronym stand for?
- DR - define risk
- C - contractions
- BRA -Baseline RAte
- V - variability
- A - Accelerations
- D - Decelerations
- O - overall impression
First stage for interpreting a cardiotocograph is determining whether the pregnancy is low or high risk Next determinen the contractios in 10 minutes? On the chart, each biq square is one minute
2/3 in 10 minutes for this chart
The baseline rate is the average heart rate of the fetus within a 10-minute window. Look at the CTG and assess what the average heart rate has been over the last 10 minutes. What is normal foetal heart rate between? Should you include accerlations and decelerations when determinign the foetal heart rtae?
120-160 bpm
Do not include accelerations and decelerations when determining the baseline heart rate
What is foetal tachycardia and bradycardia defined as?
Feotal tachycardia - basleline heart rate greater than 160 bpm Foetal bradycardia - baseline heart rate slower than 100bpm for at least 3 minutes
Baseline variability refers to the variation of fetal heart rate from one beat to the next. What should the heart rate vary from per beat?
The variability within the baseline which should be > 5bpm
What may reduced variability in the foetal heart rate be a sign of?
Foetal sleeping - shouldnt last longer than 40 minutes Drugs Prematurity - before 28 weeks Fetal acidosis (due to hypoxia)
