The health status of the vaginal microenvironment, a complicated system, is an important indicator of female reproductive health. The vaginal flora is in a state of balance, and the microorganisms coexist and are interdependent to maintain the vaginal microecological balance, which is a kind of dynamic balance influenced by endogenous and exogenous factors. Vaginal infections are traditionally treated by killing microbes in the vagina. Given the extensive study of the internal vaginal environment, people have become gradually aware of the significance of maintaining the vaginal microecological balance rather than blindly using antimicrobial agents. The balance in the vaginal internal environment is disrupted during the gestation period as the secretion of progesterone increases. The imbalanced vaginal microecological environment may lead to vaginal infectious diseases. This article provides a review of the relationship between the vaginal microecology and infectious diseases during the gestation period.