Small dates for pregn. Flashcards
Why small baby?
- pre- term delivery
Small for gestational age:
1. IUGR/FGR
2. constitutionally small
When is a preterm delivery ?
<37 wks
Extreme pre-term? 24-27+6
Very pre-term? 28-31+6
Moderate to late: 32-36+6
What is the survival rate of a 23 weeks birth?
20% chance of survival
What is the survival for a bby born beyond 32 weeks vs 26 weeks?
> 95%
26 weeks- 77%
Etiology of pre-term births?
Infection
‘Over distension’:
-Multiple
=Polyhydramnios
Vascular:
-Placental abruption
Intercurrent illness:
- Pyelonephritis / UTI
- Appendicitis
- Pneumonia
Cervical Incompetence
Idiopathic
How to label a SGA fetus?
- fetal weight or abdominal circumference is BELOW the 10th centile
- IUGR/ FGR
- LBW (below 2.5 kg) —-regardless of gestation
What can growth restriction be divided into?
Symmetrical: small head and small body
Asymp: normal size head and small body
Why are uterine artery dopplers performed?
- resistance of uterine artery is measured at 20 weeks
- —–presence of resisytance: HIGH RISK OF PRE-ECLAMPSIA and SMALL bby
Why are uterine artery dopplers performed?
- —–presence of resistance
- chewck the risk of hypertensive disease in pregnancy and risk of SGA
Fetal factors for small birth baby?
- infection (Rubella, CMV, Toxoplasmosis)
- congenital anomalies (absent kidneys)
- chromosomal abnormalities (Down $)
What are the clinical features of Poor growth?
- reduced fetal movements
- reduced SFH than expects
- reduced liquor
- predisposing factors
What is referred to as Biophysical profile?
- ## ultrasound assessment of the baby (combined with CTG)
- baby is scored on the presence of MOVEMENT/ TONE/ fetal breathing/ Liquor volume
—–score out of 10
What does the uterine artery doppler demonstrate, if there is developing HIGH resistance to the fetus?
- points where the blood flow is REVERSED; so baby is not recieving as much blood (just a little)
- absent flow during diastole (should NOT occur)
Any medications given to preterm babies?
- steroid: to promote fetal LUNG maturity
(if delivery is before 36 wks) - Magnesium sulphate (fetal neuroprotection against cerebral palsy, if before 32 weeks)
What are the risk factors for a pre-term baby?
- previous PTL (40% if 2x)
- Multiple
- Uterine anomalies
- Age (teenagers)
- Parity (=0 or >5)
- ehtnicity
- poor socio-econommic statur
- smoking
- Drugs (cocaine)
- Low BMI (<20)
Why do multiple pregnancies at once, increase the risk of a preterm birth?
- due to overdistension of the uterus
- complications may also contribute
25% of pre-term birth is planned c-section. Why plan a c-section?
- severe pre-eclampsia
- kidney disease
- poor fetal development
MAjority of pre-term is d/t this…..
UNKNOWN CAUSE (40%)
25% of pre-term birth is d/t an emergency event.
- placental abruption
- infection
- eclampsia (seizures)
What is considered to be small for gestational age ?
- EFW or AC is below the 10th centile (in the popn centile and the customised centiles)
What is the difference between IUGR and SGA?
- IUGR: bby starts on 50th centile and then cross centiles ending up on 20th over time = FAILURE to achieve true growth potential
- SGA: may grow on the 9th centile but they continue to follow their centile curve
Why may symmetrical growth restriction occur vs asymmetrical GR?
- possible chromosomal abnormality
- in utero infection
- congenital
- environmental
Asymm: placental reasons (baby is diverting blood to HEAD - to protect brain growth)
- smoking
Major risk factors for SGA baby?
oldmom/smoker/parental SGA /cocaine/Daily vigorous exercise/previous-stillbirth,SGA/diabetes/renal impariment/APS/heavy bleeding in pregnancy/low PAPP-A/ BMI>35/ fetal echogenic bowel
When is a growth scan indicated for a pregnancy?
- after a single measurement (even 2 or 3) plots below the 10th centile= suggests slow/ static growth
How to diagnose SGA?
- measuring fetal abdominal circumference
- Combine with Head circumference +/- femur length to give EFW
- Additional info from the scan= liquor volum/ amniotic fluid index-fluid around baby if low (sick baby)/ dopplers
Why may there be high resistance in the uterine artery?
- d.t abnormal placentation; failure of spiral artery invasion
Once the fetal weight is estimated, what is then done?
- value is plotted on customized growth charts
- —guides you; whether or not the bby is at risk of SGA
- —–with serial scans can see if the baby is following ITS PERCENTILE- determines if its at
Maternal factors that cause SGA?
- Smoking/alcohol/drugs
- heightand weight
- age
- maternal disease (hypertension)
When do the ladies have their uterine artery dopplers performed?
- at their 20 weeks scan
What are placental factors for SGA?
- infarctions
- abruption
- IIary to hypertension
—-abnormally functioning placenta results in growth restriction or FAILURE
If SGA/FGR is suspected from early on in the pregnancy; what is thought to be the cause?
- chromosomal abnormality
What are the postnatal consequences of IUGR?
- hypoglycemia
- effects of asphyxia
- hypothermia
- polycythaemia
- hyperbilirubinemia
- abnormal neurodevelopment
Antenatal consequence of IUGR baby?
- risk of HYPOXIA and or DEATH
Why is it important to identify a SGA baby ?
- risk of still birth
- following delivery of these babies; additional support in the neonatal unit may be needed
Any affect on the SGA baby’s adult hood?
- ongoing support in cases of cerebral palsy or developmental delay
What combination of measures help assess the fetal well-being?
- assessment of growth
- cardiotocography
- biophysical assessment
- doppler usg
Which baby will have serial scans for growth?
- any baby with AC or EFW below the 10th centile
Can blood flow within the baby be picked up?
- yes
- mainly in its middle cerebral artery and the ductus venous flow
How may a change in the MCA resistance suggest fetal compromise?
- if MCA was to become LOW resistance vessel
- —mean baby is diverting blood flow to its head to preserve the vital functions at the EXPENSE of non-vital organs
Timing for a smooth pregnancy= 37 weeks.
What are indications for earlier delivery?
- growth becomes static (IOL 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
Babies under which particular centile are at a higher risk?
- those below the 3rd centile
- —–babies between 3rd and 10th are more likely to be constitutionally small
What advise is given from our College about the delivery of SGA babies?
—should be delivered at around 37 weeks REGARDLESS of growth trajectory
What is the usual resistance of the umbilical artery?
should be LOW
—-when compromised it is HIGH; flow becomes absent and reversed in diastole
—-> MCA decr. resistance to maintain fetal blood flow to the brain
What is an indicator of the baby becoming acidotic?
—>when ductus venous doppler becomes pulsatile and INCREASES in resistance
What does the ductus venous do?
- resp. for shunting oxygenated blood from the placenta AWAY from the liver to the IVC—> Brain
