A LONGITUDINAL-STUDY OF BACTERIAL VAGINOSIS DURING PREGNANCY

Objective To determine the longitudinal changes in the incidence of ba cterial vaginosis in pregnancy. Design A prospective study of women du ring pregnancy. Setting A District General Hospital in North-West Lond on. Subjects Seven hundred and eighteen pregnant women attending anten atal clinics. At their first attendance and subsequently, Gram-stained vaginal smears were examined and Mycoplasma hominis and Gardnerella v aginalis were sought by culture. Results Initially, 87 (12 %) women ha d bacterial vaginosis diagnosed on Gram-stained reading of the vaginal smears. Examination of further smears, obtained from 176 women at 36 weeks of gestation, showed that those whose vaginal flora was normal i nitially, and who went to term, rarely developed vaginosis (three of 1 27, 2.4 %). Samples were obtained at 36 weeks gestation from 32 women who had bacterial vaginosis initially, and went to term. In almost 50 % (15 of 32) of these a normal lactobacillus-dominated flora had regen erated. Thirty-five women (5 %) had initial vaginal smears graded as i ntermediate. From this group, six of the 17 (35 %) women from whom sam ples were obtained at 36 weeks gestation still had flora of an interme diate pattern; 10 (59 %) now had normal flora and only one (6 %) had d eveloped bacterial vaginosis. Women with bacterial vaginosis were more likely to be culture-positive for M. hominis than those with normal f lora (34/78 versus 10/563, odds ratio 42.73 (18.9 to 102.3) P < 0.001) , or to be culture-positive for G. vaginalis than those with normal fl ora (35/78 versus 21/563, odds ratio 21.0 (10.75 to 41.2) P < 0.001). Conclusion Pregnant women do not commonly develop bacterial vaginosis after 16 weeks gestation, and if present, it remits spontaneously in a pproximately half of those who reach term. As bacterial vaginosis is a ssociated with increased rates of second trimester miscarriage and pre term delivery, any treatment aimed at its eradication in pregnancy sho uld be given no later than the beginning of the second trimester of pr egnancy.