Small for gestational age Flashcards
Define small for gestational age
An infant with a birth weight <10th centile for its gestational age
Define severe small for gestational age
A birth weight <3rd centile
Define foetal SGA
An estimated foetal weight or abdominal circumference <10th centile
Define foetal growth restriction
When a pathological process has restricted genetic growth potential
What can foetal growth restriction present with?
Features of foetal compromise including reduced liquor volume or abnormal doppler studies
What does low birth weight refer to?
An infant with birth weight <2500g
List some causes for an infant/foetus being small for gestational age
Normal (constitutionally) small
Placenta mediated growth restriction
Non-placenta mediated growth restriction
What percentage of SGA fetuses/infants are constitutionally small?
50-70%
Describe constitutionally small fetus/infants
Small size at all stages but growth following centiles
No pathology present
What contributes to a fetus/infant being constitutionally small?
Ethnicity
Sex
Parental height
Describe placenta mediated growth restriction
Growth is usually normal initially but slows in utero
Placental insufficiency
Give some maternal factors which can result in placental insufficiency
Low pre-pregnancy weight Substance abuse Autoimmune disease Renal disease Diabetes Chronic hypertension
Describe non-placenta mediated growth restriction
Growth is affected by foetal factors such as a chromosomal or structural anomaly - error in metabolism or foetal infection
List some risk factors for small for gestational age
Maternal age >40 Smoker >11/day Previous SGA baby Maternal/paternal SGA Previous stillbirth Cocaine use Daily vigorous exercise Maternal disease - Chronic hypertension, renal impairment, diabetes with vascular disease and antiphospholipid syndrome Heavy bleeding
When are women assessed for risk factors for SGA
At booking and again at 20 weeks gestation
How is SGA diagnosed?
Ultrasound - ratio of head circumference and abdominal circumference may be significant
What is symmetrically small foetus most likely caused by?
Constitutional
What is asymmetrically small foetus most likely caused by?
Placental insufficiency
What can placental insufficiency result in?
Impaired foetal renal function and reduced amniotic fluid
What other investigations may be useful in SGA?
Detailed foetal anatomical survey
Uterine artery doppler
Karyotyping
Screening for infections - congenital cytomegalovirus, toxoplasmosis, syphilis and malaria
How is SGA prevented?
Modifying risk factors - promote smoking cessation and optimise maternal disease
What drug should women at high risk of pre-eclampsia be started on and when?
75mg aspirin 16 weeks gestation until delivery
How is SGA monitored?
Uterine artery doppler is primary surveillance tool - if normal repeat every 14days
Symphysis fundal height
Middle cerebral artery doppler
Ductus venosus doppler
CTG
Amniotic fluid volume
What should be given if delivery between 24-35+6 weeks gestation is considered?
Single dose antenatal steroids
Before 37 weeks what would be an indication for delivery and which mode of delivery would be used?
Absent/reverse end diastolic flow on doppler
C-section
By 37 weeks what would be an indication for delivery and which mode of delivery would be used?
Abnormal UAD or MCA doppler
Induction
At 37 weeks what would be an indication for delivery and which mode of delivery would be used?
Normal UAD
Induction
What monitoring is required during labour after onset of contractions and why?
CTG - continuous foetal heart rate monitoring as high rate of C-sections
List the neonatal complications of SGA
Birth asphyxia Meconium aspiration Hypothermia Hypo/hyperglycaemia Polycythaemia Retinopathy of prematurity Persistent pulmonary hypertension Pulmonary haemorrhage Necrotising enterocolitis
List the long term complications of SGA
Cerebral palsy T2DM Obesity Hypertension Precocious puberty Behavioural problems Depression Alzheimer's disease Cancer - breast, lung, ovarian, colon and blood
