Small for dates pregnancy Flashcards
What is a small baby?
Pre-term delivery
Small for gestational age; IUGR/FGR
Constitutionally small
What is IUGR/ FGR?
Intra-uterine growth restriction
Foetal growth restriction
What is a preterm delivery?
Before 37 weeks gestation
What is an extreme preterm delivery?
24-27+6 weeks
What is a very preterm delivery?
28-31+6 weeks
What is a moderate to late preterm?
32-36+6 weeks
How many babies in the UK are born preterm?
6-7%
1 in 10 pregnancies
When is a pregnancy “viable”?
24 weeks
Why is preterm birth important?
23 weeks; 19% 24 weeks; 40% 25 weeks; 66% 26 weeks; 77% Beyond 32 weeks >95% survival
What can cause preterm birth?
Infection Multiples Polyhydramnios Placental abruption Pyelonephritis/ UTI Appendicitis Pneumonia Cervical incompetence Idiopathic
What is placental abruption?
The premature separation of the normal-sited placenta from the uterus
What are RF for preterm birth?
Previous PTL Multiples Uterine anomalies Teenagers Parity 0 or >5 Ethnicity Poor socio-economic status Smoking Drugs (cocaine) Low BMI (<20)
What are the reasons why preterm birth occur?
25% planned c/s; severe PET, kidney disease, poor foetal development
20% PROM
25% emergency; abruption, infection, eclampsia
40% unknown
What is the definition of a SGA foetus?
Estimated foetal weight or abdominal circumference below 10th centile
How is SGA plotted?
Population centiles
Customised centiles
What is a low birth weight?
Below 2.5kg (5 pounds 5) regardless of gestation
What is IUGR?
Failure to achieve growth potential
What is a worrying thing to see on centiles that points towards IUGR instead of constitutionally small?
If a baby stars on 50th centile and then drops centiles
However is a baby is on the 9th centile, but following their centile curve; they are small but not worrying
Why will you get asymmetric uterine growth restriction ?
Placental problems
Baby is diverting blood to the head to protect brain growth over less vital organs
Why will you get symmetric uterine growth restriction/
Chromosomal abnormality or in utero infection
How are SGA foetuses identified?
Antenatal RF
Screening during antenatal care
What are minor risk factors for SGA foetuses?
Maternal age >35 IVF Nulliparity BMI <20 or 25-34.9 Smoker 1-10 cigarettes/day Low fruit pre-pregnancy Pregnancy interval <6 months of >60 months
What are major risk factors for SGA foetuses?
Maternal age >40 Smoker >11 cigarettes/ day Paternal, maternal or previous SGA Cocaine use Daily vigorous exercise Previous stillbirth Chronic hypertx Diabetes with vascular disease Renal impairement APS Heavy bleeding in pregnancy Low PAPP-A Foetal echogenic bowel BMI >35 Large fibroids
What does a single major risk factor for SGA baby mean?
Formally measure and monitor foetal growth by means of USS to estimate foetal size from 26-28 weeks and at regular intervals until 36 weeks
Serial growth scans
What does 3 minor risk factors for SGA mean?
Growth scan at 34 weeks and if abnormal uterine artery doppler measurement at 20 weeks then they would be monitored as if a major RF
When is symphyseal-fundal height first measured?
24 weeks then plotted on growth charts to identify if a formal scan is required for growth
What would indicate need for a formal scan from SFH at 24 weeks?
Single measurement below 10th centile
Serial measurements suggest slow/ static growth
How is SGA diagnosed on USS?
Measurement of foetal AC (10th c) Combine with head circumference +/- femur length to give EFW Liquor volume Amniotic fluid index Uterine artery doppler and MCA
What will liquor volume tell you about the health of an SGA baby?
Fluid around baby = good
If low; suggest a sick baby
What is the ideal ultrasound for measurement of AC?
Stomach bubble
Single rib
C-shaped umbilical vein
What doe customised growth charts take into account?
Maternal parity
BMI
Ethnicity
What chart is used in tayside for SGA?
International foetal growth standards; abdominal circumference
What maternal factors can result in a small baby?
Smoking Alcohol Drugs Height and weight Age Maternal disease; hypertx or renal disease
Will all women in tayside have a uterine artery doppler?
Yes; as part of 20 week scan
What is a bad sign in a uterine artery doppler?
Resistance within the artery
Reduced flow in diastole
What does resistance within the uterine artery put the mother and baby at risk for?
SGA
PET
BP issues
What is the proposed pathophysiology of uterine artery resistance?
Abnormal placentation
Failure of spiral artery invasion
What placental factors can result in a SGA foetus?
Infarcts
Abruption
2ndary to hypertx
What foetal factors can result in SGA?
Infection; rubella, CMV, toxoplasmosis
Congenital anomalies; absent kidneys
Chromosomal abnormalities; DS
What should you think if the foetus is small before 24 weeks gestation?
Chromosomal abnormality
What are the antenatal/ labour risks with IUGR?
Hypoxia
Stillbirth
What are the postnatal consequences of IUGR?
Hypoglycemia Asphyxia Hypothermia Polycythaemia Hyperbilirubinemia CP
What are the clinical features of poor growth in utero?
Predisposing factors
Fundal height reduced
Reduced liquor
Reduced foetal movements
How should foetal wellbeing be assessed?
Assessment of growth
Cardiotocography
Biophysical assessment
Doppler ultrasound
What babies qualify for serial growth scans?
Any baby with AC or EFW below 10th centile
What is a biophysical assessment?
USS assessment
Considers; movement, tone, foetal breathing movements, liquor volume
What is the primary tool for monitoring SGA babies and timing of delivery?
Umbilical doppler assessment
Gives a measurement of placental resistance to blood flow
Why is a MCA doppler done on foetuses?
If MCA is low resistance; suggests the baby is diverting blood to its head to preserve vital functions at expense of non-vital organs
When are SGA babies delivered if no complications?
37 weeks
What are indications for considering an earlier delivery in SGA foetuses?
Growth becomes static; IOL
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
What needs to be given to the mother if a preterm delivery is planned?
Steroids; to increase lung maturity and reduce NEC
Magnesium sulphate; 4 hours pre-delivery to provide foetal neural protection
At what stages of gestation will steroids and magnesium sulphate be given in a pre-planned preterm delivery?
<36 weeks; steroids
<32 weeks; magnesium sulphate
What is the balance between in preterm delivery in a SGA infant?
Risks of prematurity
Potential of hypoxia in utero or still birth
What causes a symmetrical IUGR?
Congenital
Chromosomal
Intrauterine infection
Environemental
What causes an asymmetrical IUGR?
PET
Placental causes
Smoking
What will occur to the resistance in the ductus venosus and MCA in a distressed/ hypoxic/ acidotic foetus?
Ductus venosus; pulsatile and increased resistance
MCA; decreased resistance
Does the umbilical artery have deoxygenated or oxygenated blood?
Umbilical artery = deoxygenated
Umbilical vein = oxygenated
What is the role of the ductus venosus in the foetal circulation?
Shunts oxygenated blood past the liver to the IVC to oxygenate the brain
