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Serum progesterone predicts abnormal gestations in clomiphene citrate conception cycles as well as in spontaneous
C A Long1, S R Lincoln, N S Whitworth
1Department of Obstetrics and Gynecology, University of Mississippi Medical Center, Jackson 39216-4505.
Objective:
To determine if a "discriminatory" P concentration could be established that predicted abnormal early pregnancies in clomiphene citrate (CC)-conceived cycles.
Design:
Progesterone concentrations of gestations between 28 and 49 days from last menstrual period in both spontaneously conceived and CC-stimulated cycles were analyzed using a relative-operating characteristic (ROC) curve.
Interventions:
Serum P concentrations were measured in 222 pregnant patients from the first 49 days of gestation. One hundred sixteen patients conceived in a spontaneous cycle and 106 patients conceived in CC-treated cycles. Two by two contingency tables were used to calculate the true-positive (sensitivity) and false-positive rates at 20 specific P at 20 specific P concentrations. A ROC curve was then generated by plotting the sensitivity of the test against the percent of normal patients incorrectly classified (false positive) at each P level. The best discriminatory value was estimated in each curve at a point of high sensitivity associated with a minimal false-positive value. The areas under the curve and SE were calculated for each group and compared by the critical ratio z-test.
Results:
The best discriminatory P concentration was 10 ng/mL (32 nmol/L) for spontaneously conceived pregnancies and 30 ng/mL (95 nmol/L) for CC-treated pregnancies. The area under each ROC curve was significantly predictive. Comparison of the two curves indicated that the ability of P measurements to predict gestational complications was independent of follicular stimulation.
Conclusions:
Follicular stimulation with CC increases the discriminatory P value that predicts gestational normalcy but does not alter the clinical utility of the test.