The microorganisms in the human body or the gene pack provided by the microbiota are known as human microbiome. Microorganisms considered as dangerous occupants provide critical functions in basic human processes and non-pathogenic microorganisms were found in many body fluids and anatomical regions which were considered sterile. The colonization of microbiota is an ongoing process starting from intrauterine period, increasing its diversity especially up to the first three years. Therefore, it is important to know the factors affecting the colonization of microbiota from intrauterine period. One of these factors is maternal vagina. The impaired maternal vaginal microbiota can cause pregnancy complications and preterm labor. Transition to microbiota during pregnancy and birth continues with postpartum breastfeeding.

It is necessary to know the effect of pregnancy, birth and breastfeeding on microbiota and to increase the awareness of health professionals and expectant mothers about the factors that negatively affect the formation of healthy microbiota in these processes. This review was carried out to evaluate the role of pregnancy process, type of delivery and breastmilk in the formation and development of microbiology ecosystem which have important effects on general health level in the light of current literature.