Are racial differences in vaginal pH explained by vaginal flora?

Objectives The study assessed racial differences in vaginal pH among women without bacterial vaginosis. Study design Data from the Vaginal Infections and Prematurity (VIP) Study were analyzed. From 1984 to 1989, 13,917 largely low-income women were enrolled during routine prenatal visits from 23 to 26 weeksʹ gestation. Vaginal cultures, Gram stains, and pH levels were collected. Comparisons of pH by race were made among women with Gram stain scores <7 and without trichomoniasis before and after adjustment for actual Gram stain score. Results Among women with Gram stain scores <7, there was a modest but statistically significant racial difference in vaginal pH level. However, after controlling for difference in Gram stain score, age, and study site, there was no longer a significant difference in vaginal pH. Conclusion There is no significant difference in vaginal pH level between black and white women after controlling for differences in confounding factors, particularly vaginal flora.