Bacterial vaginosis in early pregnancy is associated with low birth weight and small for gestational age, but not with spontaneous preterm birth: A population-based study on Danish women

Objective. To analyze the association between bacterial vaginosis (BV) in early pregnancy and preterm birth, low birth weight (LBW) and small for gestational age (SGA) in a Danish population.Methods. A geographically defined population-based prospective study of Danish-speaking pregnant women over18 years of age enrolled before week 24 and followed until delivery. BV was diagnosed by Amsel's clinical criteria at enrolment.Results. At enrolment, 13.7% had BV. BV was not associated with an increased risk of spontaneous preterm birth (crude OR 0.8 (0.5–1.5)). Nulliparity was found to affect birth weight to such a degree that this variable was used for stratification. In nulliparous women BV was associated with LBW (adj. OR 4.3 (1.5–12)) and SGA (adj. OR 1.6 (0.7–3.1)) compared to nulliparous without BV. No such associations were seen for multiparous women with BV.Conclusions. BV was not associated with spontaneous preterm birth, but was associated with both LBW and SGA in nulliparous women.