Clindamycin treatment of pregnant women with asymptomatic bacterial vaginosis leads to little or no change in the risk of preterm birth before 37 weeks. The quality of the evidence is considered to be of moderate quality, and apply both if therapy is given during the second trimester and if treatment is given before 20 week gestation (early treatment). Treatment with clindamycin in the second trimester does not seem to affect the risk of low birth weight or postpartum uterine infections, but for these outcome measures the quality of the evidence is considered to be low, suggesting that further research is likely to change the effect estimates. The quality of the evidence is too low to determine whether treatment with clindamycin affects the risk of preterm birth before 33 week gestation.