The determination of a reference range for urinary oestrogen excretion in late pregnancy

A reference range for urinary oestrogen excretion between 28 and 40 weeks has been produced by analysis of 18 870 estimations. The data were transformed logarithmically to give a Gaussian distribution on which parametric analysis was performed: non-parametric analysis was carried out on the untransformed data: the results of both analyses were compatible. Multiple pregnancies tended to have levels above the 50th centile, light-for-dates fetuses below the 50th centile. Antepartum haemorrhage showed no difference from the general reference range. Intrauterine death was preceded by a level below the 5th centile if the estimation was carried out less than one week before the fetus died.