Booface it's not a problem for the vast majority of women who have it at delivery: the reasons for transmission aren't yet understood. Maybe most women have enough other, protective, bacteria in their vaginas.
Women who are near to giving birth might (this is purely personal choice and lots will NOT fancy it) want to try using a peeled clove of garlic as a pessary (thread a loop of cotton through for easy removal) and/or live yoghurt, to promote a healthy bacterial environment.