Background: Preterm birth is birth before 37 weeks' gestation. Genital tract infection is one of the causes of preterm birth. Infection screening during pregnancy has been used to reduce preterm birth. However, infection screening may have some adverse effects, e.g. increased antibiotic drug resistance, increased costs of treatment.
Objectives: To assess the effectiveness and complications of antenatal lower genital tract infection screening and treatment programs in reducing preterm birth and subsequent morbidity.
Search strategy: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (January 2008) and the Cochrane Central Register of Controlled Trials (The Cochrane Library 2007, Issue 2).
Selection criteria: We included all published and unpublished randomised controlled trials in any language that evaluated any described methods of antenatal lower genital tract infection screening compared with no screening. Preterm births have been reported as an outcome.
Data collection and analysis: Two review authors independently assessed eligibility, trial quality and extracted data.
Main results: One study (4155 women) met the inclusion criteria. This trial is of high methodological quality. In the intervention group (2058 women), the results of infection screening and treatment for bacterial vaginosis, trichomonas vaginalis and candidiasis were reported; in the control group (2097 women), the results of the screening program for the women allocated to receive routine antenatal care were not reported. Preterm birth before 37 weeks was significantly lower in the intervention group (3% versus 5% in the control group) with a relative risk (RR) of 0.55 (95% confidence interval (CI) 0.41 to 0.75). The incidence of preterm birth for low birthweight preterm infants with a weight equal to or below 2500 g and very low birthweight infants with a weight equal to or below 1500 g were significantly lower in the intervention group than in the control group (RR 0.48, 95% CI 0.34 to 0.66 and RR 0.34; 95% CI 0.15 to 0.75, respectively).
Authors' conclusions: There is evidence that infection screening and treatment programs in pregnant women may reduce preterm birth and preterm low birthweights. Future trials should evaluate the effects of types of infection screening program, gestational ages at screening test and the costs of introducing an infection screening program.