C-section may cause acute complications, but there are also adverse long-term health effects, such as increased risk of obesity and immune disorders in the offspring. The association between C-section and obesity and chronic conditions may be caused by disruption of the gut bacterial community (gut microbiota), which are essential for many physiological processes. Studies showed gut microbiota alterations in obese individuals; in turn, children born by C-section have gut microbial imbalance similar to obese children. Contact with maternal vaginal bacteria during vaginal delivery is a critical source of symbiotic bacteria that are protective against inflammation and obesity. Thus, we aim to perform a proof-of-concept, randomised controlled trial to assess the effectiveness of oral administration of maternal vaginal microbiota in restoring the gut microbiota in twins born via C-section. Infants and their stool samples will be assessed in the first day of life, at 1 month, and 3 months of age.