Serum Unconjugated Estriols in Insulin-dependent Diabetic Pregnancies: Normative Data and Clinical Relevance

ABSTRACT

The purpose of this study was to establish normative reference values for serum unconjugated estriol (E₃) concentrations in insulin-dependent diabetic pregnancy. There were 1973 samples analyzed in 63 diabetic pregnancies not complicated by fetal distress and/or neonatal asphyxia. These samples were compared with 867 samples collected in 25 pregnancies complicated by fetal distress and/or neonatal asphyxia and 103 samples collected in seven nondiabetic, uncomplicated pregnancies. E₃ values were found to be significantly higher in diabetic compared with nondiabetic healthy gravid women, correlating with infant birthweight. The percent change of daily E₃ values from the highest previous 3 days mean (maximum mean) was 1 ± 27% (mean ± SD). The 95% confidence limit for this percent change indicates that a decrease of 52% or more is theoretically seen in 2.5% of the observations. Using the traditional decrease of 40% currently used in the literature, there were false-negative and false-positive predictions of fetal distress and/or neonatal asphyxia at rates unacceptable for patient management. The use of E₃ determinations in combination with nonstress test-contraction stress test did not improve the predictability of this latter test. Serum E₃ determinations are of little clinical value in the management of insulin-dependent diabetic pregnant women.