Is inflammation on Papanicolaou smear a risk factor for preterm delivery?

Inflammation on Papanicolaou (Pap) smear has been associated with a 30-50% incidence of bacterial vaginosis (BV), a recognized risk factor for preterm delivery. We determined whether inflammation on Pap smear is associated with preterm delivery.

5,348 cases were studied with complete prenatal data including the potential confounder of treatment with antibiotics. Cases were categorized by presence (n = 1,139) or absence (n = 4,209) of inflammation on Pap smear.

In the inflammation group the proportion of African Americans was lower (66.9 vs. 74.5%; p < 0.001). There were no significant differences (t test) for maternal age, gravidity, history of preterm delivery, or gestational age at delivery between inflammation and noninflammation groups. Multiple stepwise regression analysis showed that maternal age, history of preterm delivery, and African American race were all significantly positively associated with preterm delivery. Treatment with metronidazole during the pregnancy was significantly negatively associated with preterm delivery. Inflammation on Pap smear, gonorrhea detected during the pregnancy and prenatal treatment with erythromycin were not associated.

Unlike bacterial vaginosis, inflammation on routine Pap smear does not appear to be a risk for subsequent preterm birth. We are unable to use inflammation on Pap smear as a surrogate for more specific diagnosis of bacterial vaginosis.