Candida at the Maternal–Fetal Interface: From Commensal Colonization to Chorioamnionitis and Preterm Birth—A Scoping Review

Candida species are common colonizers of the female genital tract during pregnancy, whereas proven intra-amniotic Candida infection is rare. Candida albicans predominates among reported isolates in about 90%, and other Candida species, especially Candida glabrata (Nakaseomyces glabratus), and C. tropicalis, C. parapsilosis, C. krusei, C. famata and C. kefyr as well have been reported in approximately 10%. The available epidemiological evidence does not support the hypothesis that uncomplicated vaginal Candida colonization or vulvovaginal candidiasis would be a major independent cause of preterm birth. In contrast, Candida chorioamnionitis is a rare, but potentially severe form of ascending infection associated with very early preterm labor, preterm premature rupture of membranes (PPROM), fetal inflammatory response and congenital or neonatal candidiasis. This scoping review examines the biological transition from vaginal colonization to dysbiosis, ascending infection and placental invasion, with special emphasis on virulence of Candida species. Lactobacillus species are part of the body’s primary defense mechanism against Candida overgrowth, especially in the gut and the vaginal tract. The relationship between Candida and other bacteria in our body has a complex characteristics. This study uncovers how a mixed bacterial and fungal infection inside the uterus (polymicrobial intra-amniotic infection) affects the placenta, why it is difficult to accurately identify it with current tests, and how antifungal treatments impact the health of the newborn. Current evidence suggests that Candida species should not be interpreted as either universally pathogenic organisms or irrelevant bystanders. Rather, its clinical significance is likely context-dependent and may reflect interactions between fungal burden, Candida strain, the bacterial microbiome, disruption of the maternal–fetal barrier and host inflammatory responses. Future research should shift from simple detection of organisms longitudinal multiomics characterization of the vaginal mycobiome, polymicrobial communities, placental invasion and fetal inflammatory response.