[Total serum and non-conjugated estriol in the 3d trimester of pregnancy. Inter-individual, intra-individual variations during the day and from one day to another. Study of at-risk pregnancies].

It is possible to estimate the daily rate of oestriol production by the fetoplacental unit to monitor pregnancy by radio-immunoassay of the concentrations of unconjugated and total oestriol in the serum. The usefulness of these two parameters was compared by comparing variations from day to day in the same individuals and between them and other individuals, as well as over 24 hours. We think the best choice of test for biochemical monitoring of at-risk pregnancies is the estimation of unconjugated oestriol because there is a lower day to day variation in the same individual as well as throughout the 24 hours.