Impact of quantitative fetal fibronectin (FFN) change on efficacy of antibiotic vs. placebo treatment of asymptomatic FFN positive women to prevent subsequent preterm birth (PB)

Abstract

ANTIBIOTIC VS. PLACEBO TREATMENT OF ASYMPTOMATIC FFN POSITIVE WOMEN TO PREVENT SUBSEQUENT PRETERM BIRTH (PB) MONIQUE LIN (F), for the NICHD MFMU Network, Bethesda, Maryland OBJECTIVE: To evaluate whether change in quantitative FFN concentration following antibiotic or placebo treatment of asymptomatic FFN positive women is related to subsequent PB !37 wks. STUDY DESIGN: Secondary analysis of a multicenter double blinded, placebo-controlled study of antibiotic therapy for asymptomatic women with a positive cervicovaginal FFN (R50 ng/mL) between 21-25 wks. Women were randomized to either metronidazole 250 mg tid C erythromycin 250 mg qid for 10 days or identical placebos. Quantitative FFN was assessed at baseline and 2 weeks after treatment. Preto post-treatment FFN changes (DFFN) were categorized as: 1) no change or increasing, 2) decreasing with persistent positive FFN at follow-up, and 3) decreasing with follow-up negative FFN. Primary study outcome was PB !37 wks. RESULTS: Of the 715 women enrolled, 591 had quantitative FFN values preand post-treatment and outcomes available. Race, gestational age, randomization to follow-up interval, pre-treatment FFN concentration, and BV status were similar between groups. A similar proportion of women were FFN positive at follow-up in the antibiotic group (22.5%) compared with placebo group (16.6%, p=0.07). Irrespective of treatment, rate of PB !37 wks was significantly associated with DFFN with the highest rate noted in women with no change or increased FFN (TABLE). Within each DFFN category, incidence of PB!37 wks between the two treatment groups was not significantly different (TABLE).