Ampicillin-metronidazole treatment in idiopathic preterm labour: a randomised controlled multicentre trial

Objective To determine whether treatment with ampicillin and metronidazole in women with threatened idiopathic preterm labour will prolong the gestation and reduce maternal and neonatal infectious morbidity.
Design Randomised controlled double-blind trial.
Setting Six obstetric departments in the Copenhagen area.
Population One hundred and twelve women with singleton pregnancies, with threatened idiopathic preterm labour and intact amniotic membranes at 26 to 34 weeks of gestation.
Methods Random allocation to eight days intravenous and oral treatment with ampicillin and metronidazole, or placebo.
Main outcome measures Number of days from admission to delivery, gestational age at delivery, rates of preterm delivery, low birthweight, maternal infections and neonatal infections.
Results Treatment with ampicillin and metronidazole was associated with a significant prolongation of pregnancy (admission to delivery 47.5 days versus 27 days,   P < 0.05  ), higher gestational age at delivery (37 weeks versus 34 weeks,   P < 0.05  ), decreased incidence of preterm birth (42% versus 65%,   P < 0.05  ), and lower rate of admission to neonatal intensive care unit (40% versus 63%,   P < 0.05  ), when compared with placebo treatment. Antibiotic treatment had no significant effects on infectious morbidity.
Conclusions Treatment with ampicillin and metronidazole in women with threatened idiopathic preterm labour significantly prolonged the gestation, but had no effects on maternal and neonatal infectious morbidity.