A randomized, prospective study of adjunctive ceftizoxime in preterm labor

OBJECTIVE: Our purpose was to determine the effect of ceftizoxime in the prolongation of pregnancies receiving tocolysis for preterm labor. STUDY DESIGN: A prospective, randomized, double-blinded, placebo-controlled trial was conducted in patients with preterm labor between 24 and 35 weeksʹ gestation. A total of 545 patients with intact membranes and without chorioamnionitis who were receiving magnesium sulfate were screened. Exclusions were for advanced cervical dilatation, penicillin allergy, current antibiotic therapy, and failure to give informed consent. Of these, 117 consecutive, eligible, consenting patients were randomized to receive either 2 gm of ceftizoxime or a placebo every 8 hours. The primary end point was prolongation of gestation. Statistical comparisons were performed by use of unpaired two-tailed t test and χ2 analysis. RESULTS: Of the 58 ceftizoxime and 59 placebo patients, there was no difference in the interval to delivery (34.5 ± 21.1 days vs 34.6 ± 24.5 days, p = 0.99) and no difference in the rate of delivery before 37 weeksʹ gestation (60% in the ceftizoxime group vs 58% in the placebo group, p = 0.91). Subanalyses of 61 subjects who received nine or more doses and who were group B streptococci negative, 69 patients at ≤32 weeks on presentation, and 22 sets of twins all showed no differences in delivery interval or rate of delivery at <37 weeks. The sample size of this study was sufficient to detect a 9-day difference in prolongation of pregnancy (α = 0.05, β = 0.2). CONCLUSIONS: Ceftizoxime had no effect on interval to delivery or duration of pregnancy in women treated for preterm labor.