Problems in Pregnancy: Small for dates Flashcards
What are teh causes of a small baby?
preterm delivery; small for gestational age
What can cause a baby to be small fro gestational age?
intra-uterine growth restriction or constitutionally small
What is the definition of preterm birth?
delivery between 24 and 36+6 weeks
What is the survivial rate for baby born at 24 weeks?
around 50%
What is the survival rate fro a baby born at 27 weeks?
80%
What is the survival rate for a baby born at 32 weeks?
> 95%
What is the most common cause of preterm birth?
idiopathic
What are the causes of preterm birth?
infection; over-distension; vascular; cervical insufficiency
What infections are implicated in pre-term birth?
systemic upset- pyelonephritis; appendicitis; pneumonia
What are the causes of over-distension?
multiple pregnancy; polyhydramnios; fibroids–anything that makes uterus/cervix funny shape
What is cervical insufficiency?
cervic opens and shortens prematurely
What is the cause of cervical insufficiency?
previous surgical damage to the cervix- e.g after cervical smear or repeated D&cs; or congential defect
How can cervical insuffiency be treated?
cervical suture
What types of infections are more common after preterm delviery?
neonatal sepsis; maternal postpartum endoemtritis and chorioamnionitis
What are the risk factors for preterm birth?
previous PTL; multiple pregnancy; uterine anomalies; age; parity (0 or >5); poor socioeconomic status; smoking; drugs; low BMI
What drug is especially implicated in preterm birth?
cocaine
What is the purpose of giving women steroids in preterm labour?
helps mature baby’s lungs and reduces neonatal respiratory distress syndrome
What are the purposes of giving tocolysis?
allow course of steroids and faciliatate transferring of mother
What is small for gestational age defined as?
less than 10th centile for gestation
What maternal factors are implicated in IUGR?
lifestyle- smoking; alcohol; drugs; BMI; age; maternal disease eg HT; loose assoc. with IVF babies
What fetal factors are implicated in IUGR?
chromosomal abnormalities; congenital anomalies; infection - rubella; CMV; toxoplamsa
What placental factors are implicated in IUGR?
infarcts and abruptions
What is the usual cause of placental IUGR?
secondary to HT
What is the difference bewteen symmetrical and asymmetrical IUGR?
symmetrical- head and abdo are both small; asymmetrical- normal head, small abdo
What does symmetrical IUGR indicate?
chromosome or early onset problems
What are teh consequences of being growth restricted antenatally/in labour?
risk of hypoxia or fetal death
what are the postnatal consequences of growth restriction?
hypoglycaemia; hypothermia; effects of asphyxia; polycythaemia; jaundice; abnoraml neurodevelopment
What are the clinical features of IUGR?
predisposing factors; fundal height less; reduced liquor; reduced fetal movements
What is fundal height?
symphyseal-fundal height should match gestation +/-2cm
How is fetal growth assessed on USS?
abdomen; femur length; head circumference
What does cardiotocography assess?
fetal HR and contractions
What is looked for on cardiotocography?
baseline rate; basline variability; accelerations; decelerations
What is normal fetal HR?
110-150
What is short term variability?
interval between successive heart beats varies
What do fetal acceleratiosn indicate?
good fetal circulation
What is loss of basline variability defined as?
less than 5 beats/min
What causes loss of baseline variability?
can be fetal sleep; analgesic drugs in labour; or asyphxia
What causes decelrations?
placental insufficiency
What should be done if there is decelerations?
fetal blood sample to look at pH
What factors are considered in biophysical profile of fetus?
movement; tone; fetal breathing movemetns and liqour volume
Why would there be a decrease in amniotic fluid volume if the placenta isnt working well?
decreased renal perfusion so decreased urine production or ruptured membraen
What does doppler of umbilical artery measure?
placental resistance to flow
what do you look at on doppler of umbilical artery?
ratio between peaks-systolic flow; and troughs-diastolic flow
What does absent end-diastolic flow mean?
poor placental flow- high resistance: baby in danger
What does reverse end-diastolic flow mean?
very bad!
Why is an MCA doppler done?
indicates oxygenation- faster flow in MCA indicates fetus is redirecting blood to heart and brain: cerebral redistribution
What oes a ductus venosus doppler indicate?
cardiac contractility
