[Comment] The challenge of shoulder dystocia prevention and the Big Baby trial

Shoulder dystocia is a rare but potentially serious obstetric emergency. Although many cases of shoulder dystocia are mild, risks include newborn brachial plexus injury, bony fractures, hypoxic encephalopathy, maternal perineal lacerations, and postpartum haemorrhage.1 Risk factors for shoulder dystocia include high birthweight and maternal diabetes,2,3 but it is an unpredictable event that complicates prevention efforts. In the Big Baby trial, Jason Gardosi and colleagues assessed whether shoulder dystocia rates could be reduced with induction of labour between 38 weeks' and 0 days' (38+0) gestation and 38+4 weeks of gestation compared with standard care when a fetus was suspected to be large for gestational age.