 Infection is the principal cause of preterm births. Most 90 women with preterm deliveries have no abnormal history. It is widely agreed that preterm delivery is often associated with bacterial vaginosis. One of the major difficulties at this time is that the diagnosis of bacterial vaginosis is based on heterogeneous criteria. The technique currently used is the Nugent score, but it lacks the characteristics necessary for widespread use in the general population. It must be performed on a fresh swab, and any delay in transporting it can cause drying that makes the test difficult to perform. 