Evaluation of success in treatment of threatening premature labor by betamimetic drugs.

For prevention of premature labor the betasympathicomimetic drugs buphenin, fenoterol, and ritodrine were administered to 135 patients intravenously for 1 week and afterward orally up to the end of week 37 of gestation. No satisfactory evaluation of success could be obtained by analyzing only the time gained by the treatment. Two supplemental parameters were needed. In addition to the previously introduced Tocolysis Index (TI) which describes the obstetric situation at the beginning of the treatment, a Prolongation Index (PI) was defined transforming the lag time gained by the treatment into a relative measure. By means of this PI, extremely differing cases could be compared, though the gestational ages at the start of treatment and the lag times between admission and delivery showed wide variation. In addition, satisfactory statistical correlations between the PI and the clinical signs as well as the neonatal outcome could be computed, indicating the PI to be a suitable parameter for the estimation of success.