Intraamniotic infection (IAI), most commonly presented as chorioamniotitis, plays a major role in the pathogenesis of preterm birth (PTB). In this study, we sought for signs of IAI through clinical and laboratory parameters (leukocyte count, CRP concentration and IL-6 in maternal blood), and compared those to the newborns' infectious condition. Using cervical and vaginal secretion cultures, we determined the probable causing agents of IAI. We also followed up the therapeutic effect from the use of corticosteroids, tocolitics and antibiotics for the treatment of PTB. The results demonstrated that over 46% of the pregnant women with PTB presented with evidence of IAI. The best diagnostic option to detect an IAI provides maternal blood IL-6, and the combination between leukocyte count and CRP is a must for routine examinations. We did not isolate a single vaginal pathogen but a combination of harmful microbes which provided evidence of a vaginal ecosystem disorder. The combination therapy in over 50% of women had a positive effect on PTB for the period of corticosteroid prophylaxis (72 hrs). From hour 84, antibiotic therapy can no longer control IAI development.