RELATIVE OPERATING CHARACTERISTIC ANALYSIS IN REPRODUCTIVE MEDICINE -COMPARISON OF PROGESTERONE AND HUMAN CHORIONIC-GONADOTROPIN DOUBLING TIME AS PREDICTORS OF EARLY GESTATIONAL NORMALCY

Objective: To directly compare the ability of serum P and hCG doubling time to predict early gestational complications. Design: We analyzed differences in P concentrations and hCG doubling times between spontan eously conceived normal and abnormal pregnancies (abortions and tubal pregnancies) during the first 49 days of pregnancy. Multiple 2 X 2 con tingency tables were constructed that compared pregnancy outcome withi n discriminatory serum P concentrations or hCG doubling time. From the se tables relative operating characteristic curves were generated for P concentration and hCG doubling times. The area under the curves were estimated and compared by the critical z score. Results: Calculation of the areas under the curve for hCG doubling time and P concentration yielded values of 0.799 +/- 0.056 and 0.780 +/- 0.051 (mean +/- SEM), respectively. Critical z testing did not reveal a significant differe nce between the two curves. Conclusion: Serum P and hCG doubling times equally predict early gestational normalcy. Thus, a single serum P ma y be just as valuable in estimating risks of early pregnancy complicat ions as repeated hCG measurements.