Gab Kovacs1 and Paula Briggs2
(1)
Department of Obstetrics and Gynaecology, Monash University, Clayton, Victoria, Australia
(2)
Sexual and Reproductive Health, Southport and Ormskirk Hospital, Southport, UK
Definition
Incidence
Aetilogy and Pathogenesis
Clinical Assessment
History
Examination
Investigations
Treatment
Medical
Surgical
Complications
Prognosis
Definition
A Small for Gestational Age (SGA) foetus is one that is below the tenth percentile for age of gestation, as measured by weight or abdominal circumference (using ultrasound). A severe SGA foetus is below the 3rd percentile.
Foetal growth restriction implies a pathological reduction in growth. Some, but not all of these babies are small for gestational age, whilst 50–70 % of small for gestational age babies have normal growth, and are just constitutionally small.
Incidence
By definition, 10 % of babies will be small for gestational age.
Aetilogy and Pathogenesis
Risk factors include:
Smoking, advanced maternal age, IVF pregnancy, vigorous exercise, previous SGA baby, previous pre-eclampsia, chronic hypertension, diabetes with vascular disease, renal impairment, anti-phospholipid syndrome, current pre-eclampsia, early pregnancy bleeding, placental abruption, low weight gain and excessive caffeine consumption.
Abnormal karyotype, infection with CMV, toxoplasma, syphilis and malaria can result in a small for gestational age foetus as early as 18–20 weeks gestation.
Clinical Assessment
History
Assess for risk factors as above
Examination
Measurement of fundal height – pubic symphysis to fundus
Liquor volume – assess for oligohydramnios
Investigations
· PAPP-A – low level in the first trimester is a risk factor
· Serial ultrasound assessment of foetal weight/ abdominal circumference at least 3 weeks apart
· Uterine artery Doppler at 20–24 weeks
· Umbilical artery Doppler
· Middle Cerebral Artery Doppler
· Ductus venosus doppler
· Ultrasound assessment of amniotic fluid volume
· CTG monitoring, preferably computerised
Treatment
Medical
Other Medical
In women at high risk of pre-eclampsia, antiplatelet agents (for example aspirin) may have some beneficial effect, if started by 16 weeks
If delivery is contemplated between 24 and 35 weeks, steroids should be administered.
Surgical
Minor
artificial rupture of membranes and induction
Major
Caesarean Section
Complications
Intrauterine death
Prognosis
By monitoring the foetus as described above and making an informed decision about when to deliver, a good outcome should be achieved