Early pregnancy changes in bacterial vaginosis-associated bacteria and preterm delivery.

BACKGROUND: We evaluated the importance of measuring early vaginal levels of eight bacterial vaginosis (BV)-associated bacteria, at two points in pregnancy, and the risk of spontaneous preterm delivery (SPTD) among pregnant women and the subgroup of pregnant women with a history of preterm delivery (PTD).

METHODS: This prospective cohort study enrolled women at five urban obstetric practices at Temple University Hospital in Philadelphia PA. Women with singleton pregnancies less than 16 weeks gestation self-collected vaginal swabs at two points in pregnancy, prior to 16 weeks gestation and between 20-24 weeks gestation, to measure the presence and level of eight BV-associated bacteria. Women were followed-up for gestational age at delivery via medical records.

RESULTS: Among women reporting a prior PTD, women with higher levels of Leptotrichia/Sneathia species, BVAB1 and Mobiluncus spp., prior to 16 weeks gestation, were significantly more likely to experience a SPTD. In addition, pregnant women with a prior PTD and increasing levels of Leptotrichia/Sneathia species (aOR: 9.1, 95% CI 1.9, 42.9), BVAB1 (aOR: 16.4, 95% CI 4.3, 62.7) or Megasphaera phylotype 1 (aOR: 6.2, 95% CI 1.9, 20.6), through 24 weeks gestation, were significantly more likely to experience an SPTD. Among the overall group of pregnant women, the levels of BV-associated bacteria were not related to SPTD.

CONCLUSION: Among the group of women reporting a prior PTD, increasing levels of BVAB1, Leptotrichia/Sneathia species, and Megasphaera phylotype 1, through mid-pregnancy were related to an increased risk of SPTD.