Table 2: Studies of specific use of antibiotics for preterm birth prevention.

StudyNAntibiotic regimenGestational age at treatment (wks)Days treatmentPrimary outcomesBenefit

Hauth et al. (1995) [53]624PO metronidazole + PO erythromycin22–247/14Gestational age at delivery Rate of preterm deliveryYes
(26% versus 36% rate of preterm delivery, )
McDonald et al. (1997) [54]897PO metronidazole24–292 dosesReduction in Spontaneous birth less than 37 weeksYes
(9.1% versus 41.7% reduction, OR 0.14, CI 0.01–0.84)
Carey et al. (2000) [67]1953PO metronidazole16–24
2 dosesRate of delivery before 37 weeksNo
Ugwumadu et al. (2003) [56]6210PO clindamycin12–225Spontaneous preterm delivery and late miscarriageYes
(10.4% reduction in miscarriages and PTD, )

Trichomonas vaginalis
Klebanoff et al. (2001) [55]617PO metronidazole16–23
2 dosesRate of delivery before 37 weeksNo
Kigozi et al. (2003) [57]206PO azithromycin, cefixime, metronidazoleAny gestation1 dose(1) Birth weight
(2) Rate of preterm birth
(3) 2-year mortality rate

Other relevant studies
Andrews et al. (2006) [69]
124PO azithromycin + PO metronidazole4 months after delivery2 doses/7 days every 4 months until next pregnancySubsequent rate of preterm birth or miscarriageNo
Fetal Fibronectin +
Andrews et al. (2003) [58]
703PO metronidazole + PO erythromycin21–25.6
10Spontaneous delivery less than 37 weeksNo
Fetal Fibronectin +
Shennan et al. (2006) [59]
109PO metronidazole24–277Spontaneous preterm delivery less than 30 weeksNo