Mom matters: maternal influences on infant gut microbiome and health

Our gut microbiota—the trillions of microbes living in our intestines—plays a crucial role in our overall health. Since the gut microbiota is modifiable, it offers a powerful opportunity to prevent future diseases. However, many questions remain about its dynamics and the factors that shape it. In particular, we still know little about how the gut microbiota differs between men and women or its dynamics during pregnancy and early life. The first part of this thesis investigates sex differences across multiple omics layers focusing on the gut microbiome. Women have a higher abundance of antibiotic-resistance genes in their gut microbiome compared to men, which aligns with national differences in prescription practices, as women generally consume more antibiotics. The second part focuses on the gut microbiota during early life, often called the 'window of opportunity,' where the dynamic gut microbiota plays a crucial role in immune system development. By establishing the randomized controlled trial CS Baby Biome and the population-based Lifelines NEXT cohort, we demonstrate that mode of delivery and feeding practices are key factors influencing the infant gut microbiome. Importantly, maternal exposures and the maternal gut microbiome play crucial roles in seeding and colonizing the infant gut microbiome, significantly influencing infant health outcomes like atopic dermatitis. Overall, the findings of this thesis underscore the pivotal role of the mother and her microbiome in shaping infant gut microbiome and health, laying the foundation for lifelong well-being and providing targets for disease prevention.