OBJECTIVES:the aim was to examine factors associated with acquisition and elimination of bacterial vaginosis in pregnancy.METHODS:a group of 229 pregnant women were randomly selected from a population-based prospective cohort study of 2927. They were examined at enrollment (mean gestational weeks 16w+0d) and again in mid-third trimester (mean gestational age 32w+3d).MEASURES:BV (Amsel's clinical criteria), microbiological cultures of the genital tract and questionnaire data.RESULTS:BV prevalence decreased from 17% in early second trimester to 14% in mid-third trimester due to a tenfold higher elimination rate (39%) than incidence rate (4%). Heavy smokers (>10/d) in early pregnancy were at increased risk (5.3[1.1-25]) for the acquisition of BV during pregnancy, as were women receiving public benefits (4.8[1.0-22]), having a vaginal pH above 4.5(6.3[1.4-29]) or vaginal anaerobe bacteria (18[2.7-122]) at enrollment. A previous use of combined oral contraceptives was preventive for the acquisition of BV (0.2[0.03-0.96]). Elimination of BV in pregnancy tended to be associated with a heavy growth of Lactobacillus(3.2[0.8-13]) at enrollment.CONCLUSIONS:acquisition of BV during pregnancy is rare and is associated with smoking, while the presence of anaerobe bacteria and a vaginal pH >4.5 are interpreted as steps on a gradual change towards BV. In the same way heavy growth of Lactobacillus spp in early pregnancy may be an indicator of women on the way to eliminate BV.

OBJECTIVE: To evaluate the association between various microorganisms isolated from the genital tract in pregnant women with bacterial vaginosis.STUDY DESIGN: A cross-sectional population-based study among pregnant women addressed at their first antenatal visit before 24 full gestational weeks from the referring area of the Department of Obstetrics and Gynecology at Odense University Hospital, Denmark, from November 1992 to February 1994. The main outcome measures were prevalence of various microorganisms and statistical estimates of interactions (crude, adjusted, and relative odds ratios) between the microorganisms isolated from the lower genital tract in pregnant women with and without clinical diagnosis of bacterial vaginosis.RESULTS: Three thousand five hundred ninety-six (3596) pregnant women were asked to participate. Of the 3596 pregnant women 3174 (88.4%) agreed to participate before 24 full gestational weeks. After controlling for the presence of other microorganisms, strong associations between Gardnerella vaginalis, anaerobic bacteria, Mycoplasma hominis, and present bacterial vaginosis were found. Similarly Lactobacillus spp. were found to be associated with the absence of bacterial vaginosis. The combination of G. vaginalis and anaerobic bacteria and/or M. hominis was found in 59.6% of the cases with bacterial vaginosis and in 3.9% of the cases without bacterial vaginosis (odds ratio 36.4, 95% confidence interval 27.8 to 47.8). The crude odds ratio was found to be as high as 74.8 (95% confidence interval 32.3 to 174.1) when the combination of G. vaginalis, M. hominis, anaerobic bacteria, and no Lactobacillus spp. was associated with bacterial vaginosis,CONCLUSION: There is a microbial foundation for bacterial vaginosis, and it is possibly due to an intermicrobial interaction in which the microorganisms G. vaginalis, anaerobic bacteria, and M. hominis are dominating, indicating that these constitute the pathologic core of bacterial vaginosis.