In a relatively unselected group, mothers who stayed 1 night after routine vaginal delivery reported more distress and more pediatric problems and had greater use of outpatient health services than mothers who stayed 2 nights.

Summary Total plasma oestriol in pregnancy was estimated by a competitive protein binding method. The advantages of the measurement of plasma oestriol levels over the 24‐ or 48‐hour urinary oestriol assays are discussed. The pattern of plasma oestriol levels in the third trimester of pregnancy was investigated in over 400 healthy women and in general a uniform increase was found from the 28th week until term. Diurnal variation was found to be present, but this did not preclude the use of the method for assessing the feto‐placental unit. Exercise and meals had a minimal effect on the oestriol levels. Following delivery the level decreased sharply to reach, within four hours, one‐half that found just prior to delivery.

Summary A simple and rapid (4 hour) method for the measurement of oestriol in pregnancy plasma is described. The method utilizes the technique of competitive protein binding analysis and requires 0.2 ml. of plasma or less for each estimation. One technician can process 40 or more specimens in one day. Serial samples can be analyzed as they become available. Information about precision, accuracy, specificity, and sensitivity are presented. The method has been used to assay oestriol in amniotic fluid and should be equally applicable to measurements of urinary oestriol excretion.

This report gives details of the authors' procedure for the measurement of 17β-oestradiol in plasma by competitive protein binding analysis, together with the results of studies on various parameters of the assay system. The preparation of the receptor cytosol, the assay system, extraction of plasma and reliability criteria are all discussed. The procedure is compared with those reported by other workers. Finally the results obtained by this technique are compared with those obtained by other methods and current applications are presented.

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