Microbiota during pregnancy, childbirth, and postpartum, and its relationship with health and disease states

Metabolic adaptations are essential for achieving a healthy full-term pregnancy. These changes are influenced by the maternal microbiota, specifically its composition and diversity, which are, in turn, shaped by the physiological demands of pregnancy. This review examines scientific evidence on the role of the microbiota during pregnancy, childbirth, and the postpartum period, and its association with both health and disease states. Notable microbiota shifts during pregnancy include changes in the vaginal microbiota (with a predominance of Lactobacillus species), the gastrointestinal tract (increased levels of Proteobacteria and Actinobacteria ), the oral cavity (higher prevalence of bacteria such as Aggregatibacter actinomycetemcomitans ), and breast milk (presence of Lactobacillus spp.). Disruption of microbial homeostasis (dysbiosis) during pregnancy has been linked to a variety of obstetric, fetal, and neonatal complications, including gestational diabetes, preeclampsia, intrauterine growth restriction, low birth weight, and preterm birth. Multiple studies have documented the role of diet in the development of dysbiosis and its connection to mental health disorders. Diets high in saturated fats appear to significantly influence gut microbiota due to their pro-inflammatory effects. Additionally, low fiber intake has been associated with reduced microbial diversity and an increased abundance of Collinsella , a genus linked to type 2 diabetes. Therefore, dietary interventions aimed at enhancing microbial balance and reducing systemic inflammation are recommended. A multidisciplinary approach is also crucial for translating current findings into clinical strategies, particularly for populations at increased risk. • Infant microbiome development: The maternal microbiota influences infant health. • Changes in the maternal microbiota: Alterations in the microbiota affect maternal health. • Mode of delivery and neonatal microbiome: The type of delivery affects the infant's microbiota. • Interventions that modulate microbiota: The use of probiotics and antibiotics affects microbiota.