Early life microbiota colonization. The A.MA.MI Study

ABSTRACT Background. The intestinal microbiome is relatively dynamic during the first years of life, becoming relatively stable throughout a lifetime, thus dictating adult life's future health. There are many factors influencing gut microbiome composition, including maternal pre-pregnancy, body mass index (BMI), gestational weight gain (WG), type of feeding, weaning timing, and birth/family environment. Objectives. The study aims to investigate the intestinal microbiome development of infants (ages 0-12 months) and to analyze how prenatal and postnatal factors, including maternal BMI and weight gain during pregnancy, type of feeding, time and type of weaning, and the presence of siblings in the family, could influence the infant gut microbiome composition at one year of age. Methods. 63 dyads were enrolled at Neonatal Unit, IRCCS Policlinico San Matteo, Pavia. Anthropometric parameters were assessed before discharge (T0), at 30 days from birth (T1), at 6 months (T2) and 1 year (T3); validated questionnaires were used to evaluate mother’s dietary habits and physical activity at each time. Mothers were interviewed about family environment and infants feeding/supplementation at each time. For each child a stool sample was collected at each time and analyzed using metagenomics 16s ribosomal RNA gene sequence-based methods. Cluster and correlation analysis were used to assess changes in the microbial composition across different follow-up times. Results. At one years of age, pre- and perinatal variables were not significantly associated with any bacterial taxon, while postnatal variables showed the major contribution in shaping microbiota. Feeding and weaning were the main influencing factors. Conclusion. Our findings highlighted that microbial colonization during the first year of life is likely affected by various factors resembling a simultaneous effect of multiple variables. Mainly, different variables play a significant role at different time. Thus, these data contribute to add evidence concerning the complex multifactorial interaction of GI-microbiota depending on the various stimuli during the early stages of life. This study will provide the starting point for a future prospective and observational study assessing the potential association between maternal diet and life-style with newborns microbiome composition, their influence on childhood obesity development and the associated increased risk of NCDs in adulthood.