A device (LMU061, ObsteCare AB, Sweden) adapted for measurement of lactate in amniotic fluid, automatically calibrated at measurement to ensure optimal measurements performance, was available in every delivery ward of the participating hospitals . The device measured lactate concentration in AF with a coefficient of variation of approximately 3% at a lactate concentration of 11mmol/l. The lactate recognition system was based on lactate oxidase with amperometric detection of the enzymatically produced hydrogen peroxide .