The dynamics of the female microbiome: unveiling abrupt changes of microbial domains across body sites from prepartum to postpartum phases

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 [maternal prepartum (mpre), n = 30] into the postpartum period [1 month postpartum, maternal postpartum (mpost), n = 30]. We profiled their oral, urinary, and vaginal microbiome; archaeome; mycobiome; and urinary metabolome and compared them with those of nonpregnant (np) women (n = 29). Overall, pregnancy status (np, mpre, and 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 mainly in np women, and Methanobrevibacter showed an opposite behavior in the 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.

Importance: The perinatal microbiome is of specific interest for the health of the mother and infant. We therefore investigate the dynamics of the female microbiome from nonpregnant over prepartum to the postpartum period in urine and the oral and vaginal cavities. A specific focus of this study is put not only on the bacterial part of the microbiome but also on the underinvestigated contribution of fungi and archaea. To our knowledge, we present the first study highlighting those aspects. 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.