The Dynamics of the Female Microbiome: Unveiling Abrupt Changes of Microbial Domains across Body Sites from Preconception to Perinatal Phase

The microbial ecosystem of women undergoes enormous changes during pregnancy and the perinatal period. Little is known about the extent of changes in the maternal microbiome beyond the vaginal cavity and its recovery after birth. In this study, we followed pregnant women (mpre, n = 30) into the postpartum period (1 month postpartum, mpost, n = 30). We profiled their oral, urinary, and vaginal microbiome, archaeome, mycobiome and urinary metabolome and compared them with nonpregnant women (np, n = 29). Overall, pregnancy status (np, mpre, mpost) had a smaller effect on the microbiomes than body site, but massive transitions were observed for the oral and urogenital (vaginal and urinary) microbiomes. While the oral microbiome fluctuates during pregnancy but stabilizes rapidly within the first month postpartum, the urogenital microbiome is characterized by a major remodeling caused by a massive loss of Lactobacillus and thus a shift from vaginal community state type (CST) I (40% of women) to CST IV (85% of women). The urinary metabolome rapidly reached an np-like composition after delivery, apart from lactose and oxaloacetic acid, which were elevated during active lactation. Fungal and archaeal profiles were indicative of pregnancy status. Methanobacterium signatures were found exclusively in np women, and Methanobrevibacter showed opposite behavior in oral cavity (increased) and vagina (decreased) during pregnancy. Our findings suggest that the massive remodeling of the maternal microbiome and metabolome needs more attention and that potential interventions could be envisioned to optimize recovery and avoid long-term effects on maternal health and subsequent pregnancies.