Plasma estradiol as a predictor of preterm labor

Studies have shown a rapid rise of plasma estradiol-17beta in the maternal circulation before the occurrence of preterm labor. We have attempted to perform a linear regression analysis of the data from normal pregnancies and to set up a 95% upper prediction limit for the normal range of the estradiol level for each week of gestation. The prediction limits were reasonably good, with only five (13%) false negatives. False negatives tend to occur only in late pregnancy.