Abstract
The formation of infant intestinal microbiota begins in the womb when there is a selective transport of certain bacteria from the intestine through the placenta and amniotic fluid which has been proved in experiments. The mode of delivery has a significant impact on the establishment of the intestinal biocenosis: babies born by caesarean section show a slower colonisation rate and a higher risk of developing food allergies later in life. Antibiotic therapy at an early age can permanently alter the composition of the intestinal microbiota and has a proven risk of developing a range of diseases, both immunopathological and metabolic. The type of feeding also has a significant impact. Exclusive breastfeeding from birth promotes the establishment of a bifidobacterial and bacteroide-dominated infant microbiota. Supplementation at birth and early transfer to complementary feeding contribute to microbiocenosis alteration and sensitisation to cow's milk protein. Probiotics due to their protective and immunomodulatory effects can improve the composition of the microbiota of breast milk and the baby's gut and their perinatal administration reduces the risk of food allergies and other diseases.