In Nepal, investigators are conducting a cohort study to estimate the relationship between signs of periodontal disease in pregnant women and preterm delivery. Within that cohort study, investigators plan to conduct an individually randomized trial of the acceptability and effect chlorhexidine, cetylpyridinium chloride, and salt water oral rinses on gingival crevicular fluid and plaque during pregnancy. Women for this pilot trial will be chosen from a subset of the area currently engaged in the larger cohort study, to simplify logistics. The pilot trial will have four arms (three oral rinse arms, and one control group).