The woman, who has not been identified, is thought to have suffered an extremely rare amniotic fluid embolism last week. It occurs when a tear in the foetal sac damages blood vessels surrounding the womb, allowing amniotic fluid to escape into the mother's blood. This can trigger heart and lung collapse and stop blood clotting. The condition can be fatal but studies show that up 70 per cent of women who develop the condition
may survive. They also show drug-induced labours are at greater risk. It is not known if the child survived.