Infection and antibiotics in the aetiology, prediction and prevention of preterm birth.

Spontaneous preterm labour and delivery is a syndrome comprising diverse pathological pathways that result in labour and delivery before term. It is recognised that multiple pathological processes are involved, and infection has been well studied and firmly established as a cause. Although the molecular mechanisms responsible for this process have been identified, there is a lack of consensus about effective antibiotic intervention. Systematic reviews of the few well conducted studies suggest that antibiotics active against bacterial vaginosis or related organisms (clindamycin) given to appropriate women (those with objective evidence of abnormal genital tract flora), and used early in pregnancy (< 22 completed weeks of gestation) before irreversible inflammatory damage occurs, can reduce the rate of preterm birth. There is a need for well constructed trials to understand the vaginal microbiome and how the different types of maternal immune response influences outcome.