This clinical trial compares the effects of breast milk, chlorhexidine, and drying on the bacterial colonization of the umbilical cord in premature infants. The trial is one-centered, single-blind, and in phase 2 of clinical trials. The major inclusion criteria are gestational age less than 37 weeks and admission in the neonatal intensive care unit. Major exclusion criteria include the lack of consent of the legal guardian, approved sepsis, and the history of non-sterile childbirth in the mother. A sample of 75 preterm infants will be recruited by convenience sampling method and assigned into one of the three groups of drying, chlorhexidine, and milk by using table of random numbers (n=25 per group). During the first 12 to 24 hours of admission, umbilical cord samples will be collected from the neonates as follows. Using sterile swabs, umbilical cord samples of the infants (1 centimeter from the skin surrounding the umbilical cord) will be taken and transferred to the laboratory in phosphate buffer solution (tube containing 5 cc phosphate saline buffer with pH of 7). Then, serial dilutions will be prepared in one to ten ratio from the samples. Afterwards, 0.01 cc comprising of non-diluted specimen, one-tenth diluted specimen, and one-hundredth diluted specimen will be cultured on the agar culture medium and Eosin methylene blue agar. The plates will be kept at 37 ° Celsius for 48 hours. In terms of study interventions, in the drying group, the umbilical cord will be kept dry using sterile gauze. In the chlorhexidine group, every six hours, 2 to 3 cc of 0.2 percent chlorhexidine mouthwash will be applied onto the umbilical cord and 1 centimeter of its surrounding area proportionate to the umbilical cord size. In the breast milk group, every six hours, between 1 and 2 cc of the milk will be applied onto the umbilical cord and 1 centimeter of its surrounding area proportionate to the umbilical cord size. After 72 hours, again using a sterile swab, the umbilical cord will be sampled and cultured. The effects of the three interventions on the number of viable bacteria and type of bacteria will be investigated.