Shifts in the Maternal Gut Microbiome Across Pregnancy are Associated with Energetic Status in Phayre's Leaf Monkeys

Abstract

During pregnancy, mothers experience physiological changes that support fetal development, including shifts in energy utilization and increasing insulin resistance during late gestation. While these changes benefit the fetus, they can also impose energetic costs that affect the mother's physical condition and metabolic phenotype. Previous studies suggest that the gut microbiome, a key regulator of female metabolism and energy harvest, may play a critical role in mediating these physiological challenges. In this study, metagenomic sequencing of the gut microbiome of 120 samples revealed dramatic shifts in gut bacterial composition and function associated with pregnancy and lactation in 14 wild Phayre's leaf monkeys, Trachypithecus phayrei crepusculus, from two groups at the Phu Khieo Wildlife Sanctuary, Thailand. Alpha diversity, beta diversity, and taxonomic composition all differed between cycling and the 3rd trimester. Furthermore, bacterial dissimilarity between these states was negatively correlated with postpartum physical condition; that is, mothers whose gut microbiota remained more stable during pregnancy recovered sooner after giving birth. Functional profiling revealed a depletion of pathways involved in purine salvage and glutamate degradation during the 3rd trimester. Overall, our study demonstrates that the gut microbiome undergoes substantial changes during pregnancy, and the stability of these microbial communities predicts postpartum maternal health and potentially influence lifetime reproductive output.