Abrupt perturbation and delayed recovery of the vaginal ecosystem following childbirth

TEMPTED: time-informed dimensionality reduction for longitudinal microbiome studies

Longitudinal studies are crucial for understanding complex microbiome dynamics and their link to health. We introduce TEMPoral TEnsor Decomposition (TEMPTED), a time-informed dimensionality reduction method for high-dimensional longitudinal data that treats time as a continuous variable, effectively characterizing temporal information and handling varying temporal sampling. TEMPTED captures key microbial dynamics, facilitates beta-diversity analysis, and enhances reproducibility by transferring learned representations to new data. In simulations, it achieves 90% accuracy in phenotype classification, significantly outperforming existing methods. In real data, TEMPTED identifies vaginal microbial markers linked to term and preterm births, demonstrating robust performance across datasets and sequencing platforms.

Analysis of vaginal microbiota during postpartum and postmenopausal periods based on metagenomics

BACKGROUND

Postmenopausal and the postpartum periods are essential physiological phases that result in low estrogen levels in women; however, they are important to female reproductive health. Traditional as well as new detection methods (such as 16 S RNA sequencing) have limitations in detecting the composition of vaginal microbiota. Therefore, in this study, we used metagenomic detection technology to study the composition of vaginal microbiota in postmenopausal and postpartum women. Six women were randomly selected from each group (healthy women of childbearing age, postmenopausal group, and postpartum) for vaginal microecology, composition, α-diversity, linear discriminant analysis effect size (LEfSe), and Comprehensive Antibiotic Resistance Database (CARD) analyses.

RESULTS

We discovered that Lactobacillus dominance disappeared in postpartum and postmenopausal group women and that diversity increased. However, the proportions of Atopobium vaginae, Escherichia coli, and Streptococcus agalactiae significantly increased. Diversity was the highest in the postpartum period, with a significant increase in the proportions of A. vaginae, Gardnerella vaginalis, Prevotella, and occasionally, Chlamydia trachomatis. Linear discriminant analysis effect size analysis revealed that Lactobacillus crispatus and L. iners enrichment in the postpartum and menopausal periods was much lower than that in the childbearing age group. CARD analysis revealed that ABC-F ATP-binding cassette ribosomal protection protein subfamily gene abundance was significantly lower in the menopausal than in the childbearing age group, whereas the gimA family macrolide glycosyltransferase gene abundance was significantly higher.

CONCLUSIONS

The dominance of vaginal Lactobacillus in postpartum and menopausal women disappeared, while their diversity increased. In addition, the reproductive tract of postpartum women was susceptible to invasion by pathogenic microorganisms, which deserves clinical attention. When menopausal women receive treatment for vaginal infections, the likelihood that certain bacterial communities develop antibiotic resistance through ribosomal protection mechanisms is lower than that of women in the childbearing age, while the possibility of developing resistance to macrolides through glycosylation may increase. This, however, requires further research.

Dietary amino acids, macronutrients, vaginal birth, and breastfeeding are associated with the vaginal microbiome in early pregnancy

The vaginal microbiome is a key player in the etiology of spontaneous preterm birth. This study aimed to illustrate maternal environmental factors associated with vaginal microbiota composition and function in pregnancy. Women in healthy pregnancy had vaginal microbial sampling from the posterior vaginal fornix performed at 16 weeks gestation. After shotgun metagenomic sequencing, heatmaps of relative abundance data were generated. Community state type (CST) was assigned, and alpha diversity was calculated. Demography, obstetric history, well-being, exercise, and diet using food frequency questionnaires were collected and compared against microbial parameters. A total of 119 pregnant participants had vaginal metagenomic sequencing performed. Factors with strongest association with beta diversity were dietary lysine (adj-R2 0.113, P = 0.002), valine (adj-R2 0.096, P = 0.004), leucine (adj-R2 0.086, P = 0.003), and phenylalanine (adj-R2 0.085, P = 0.005, Fig. 2D). Previous vaginal delivery and breastfeeding were associated with vaginal beta diversity (adj-R2 0.048, P = 0.003; adj-R2 0.045, P = 0.004), accounting for 8.5% of taxonomy variation on redundancy analysis. Dietary fat, starch, and maltose were positively correlated with alpha diversity (fat +0.002 SD/g, P = 0.025; starch +0.002 SD/g, P = 0.043; maltose +0.440 SD/g, P = 0.013), particularly in secretor-positive women. Functional signature was associated with CST, maternal smoking, and dietary phenylalanine, accounting for 8.9%-11% of the variation in vaginal microbiome functional signature. Dietary amino acids, previous vaginal delivery, and breastfeeding history were associated with vaginal beta diversity. Functional signature of the vaginal microbiome differed with community state type, smoking, dietary phenylalanine, and vitamin K. Increased alpha diversity correlated with dietary fat and starch. These data provide a novel snapshot into the associations between maternal environment, nutrition, and the vaginal microbiome.

IMPORTANCE

This secondary analysis of the MicrobeMom randomized controlled trial reveals that dietary amino acids, macronutrients, previous vaginal birth, and breastfeeding have the strongest associations with vaginal taxonomy in early pregnancy. Function of the vaginal niche is associated mainly by species composition, but smoking, vitamin K, and phenylalanine also play a role. These associations provide an intriguing and novel insight into the association between host factors and diet on the vaginal microbiome in pregnancy and highlight the need for further investigation into the complex interactions between the diet, human gut, and vaginal microbiome.

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.

Ambient Environment and the Epidemiology of Preterm Birth

Preterm birth (PTB) is associated with substantial mortality and morbidity. We describe environmental factors that may influence PTB risks. We focus on exposures associated with an individual's ambient environment, such as air pollutants, water contaminants, extreme heat, and proximities to point sources (oil/gas development or waste sites) and greenspace. These exposures may further vary by other PTB risk factors such as social constructs and stress. Future examinations of risks associated with ambient environment exposures would benefit from consideration toward multiple exposures - the exposome - and factors that modify risk including variations associated with the structural genome, epigenome, social stressors, and diet.

Solving the Puzzle of Preterm Birth

Solving the puzzle of preterm birth has been challenging and will require novel integrative solutions as preterm birth likely arises from many etiologies. It has been demonstrated that many sociodemographic and psychological determinants of preterm birth relate to its complex biology. It is this understanding that has enabled the development of a novel preventative strategy, which integrates the omics profile (genome, epigenome, transcriptome, proteome, metabolome, microbiome) with sociodemographic, environmental, and psychological determinants of individual pregnant people to solve the puzzle of preterm birth.

The human vaginal microbiota: from clinical medicine to models to mechanisms

The composition of the vaginal microbiota is linked to numerous reproductive health problems, including increased susceptibility to infection, pregnancy complications, and impaired vaginal tissue repair; however, the mechanisms contributing to these adverse outcomes are not yet fully defined. In this review, we highlight recent clinical advancements associating vaginal microbiome composition and function with health outcomes. Subsequently, we provide a summary of emerging models employed to identify microbe-microbe interactions contributing to vaginal health, including metagenomic sequencing, multi-omics approaches, and advances in vaginal microbiota cultivation. Last, we review new in vitro, ex vivo, and in vivo models, such as organoids and humanized microbiota murine models, used to define and mechanistically explore host-microbe interactions at the vaginal mucosa.