Large for Dates pregnancy

Question 1

Define

Answer 1

Term to identify macrosomic babies (≥4kg or ≥4.5kg – the definition varies) -> 10% of pregnancies

· Prenatally, 3 tools used to diagnose large for age

o 1st -> Symphysis-fundal height (SFH) à >90th/95th centile for gestational age à foetal biometry…

o 2nd -> Abdominal Circumference (AC) à >90th/95th centile for gestational age

o 2nd -> Estimated foetal weight (EFW) à >90th/95th centile for gestational age

Question 2

Risk factors

Answer 2

• High BMI
• Foetal macrosomia (>4kg in a term infant)
• Gestational or DM
• Syndromes: Beckwith-Wiedemann, Simpson-Golabi-Behemel, Soto’s syndrome
• Molar pregnancy
• Polyhydramnios
• Multiparity
• Advanced maternal age

Question 3

Signs and symptoms

Answer 3

On inspection -> excessive distension for gestational age

Abdomen -> increased SFH (symphysis fundal height), increased abdominal circumference

Question 4

Investigation

Answer 4

OGTT – for gestational diabetes

Bloods – serum βHCG

USS – liquor volume, biometry

Genetic testing

Question 5

Management

Answer 5

Detected at 18-21 weeks à repeat scan

Detected at 24-36 weeks à if acceleration of growth, arrange USS for foetal biometry

• If follows same path (no drop/rise growth), then reassure this is normal, arrange another routine scan
• Offer OGTT (gestational diabetes)

Detected at 36-40 weeks à if SFH is >90th centile on routine measurements à USS for foetal biometry

• If EFW and AC on USS are >95th centile, return to routine care
• Perform OGTT (gestational diabetes)
• Care in labour + postnatally as per gestational diabetes dx at earlier gestation

Need to plan delivery and discuss risk of shoulder dystocia, nerve injuries, prolonged labour à offer CS

Question 6

Complications

Answer 6

• Shoulder dystocia
• Hypoglycaemia in GDM
• Respiratory distress syndrome – combination of GDM, need to deliver earlier
• Intrauterine deformations – metatarsus adductus (foot bends inwards), hip subluxation
• Increased mortality
• Perineal tear
• Prognosis -> early planning/care -> no difference in outcomes for LGA compared to normal