Purpose: To verify the presence of Socransky Red Complex (Porphyromonas gingivalis, Treponema denticola and Tannerella forsythia) and P. intermedia using polymerase chain reaction (PCR) in periodontally healthy pregnant women and pregnant women with periodontal disease, as well as its relation to arterial blood pressure and capillary glycaemia. Materials and Methods: This case control study included 86 pregnant women, including 50 pregnant women with healthy periodontium, 27 with gingivitis and 9 with periodontitis. Arterial blood pressure and glycaemia were evaluated and recorded. Clinical specimens from the gingival crevice or periodontal pockets were gathered with sterile absorbent paper cones. DNA extraction was accomplished using the Easy-DNA Kit test and the presence of bacteria was detected by PCR with primers and specific probes for each microorganism. Results: The arterial pressure of all pregnant women was found to be within normal levels and 51% presented with hyperglycaemia, these two variables were not associated with periodontal conditions and/or presence of microorganisms. Socransky Red Complex was not present in pregnant women with healthy periodontium; however, it was present in pregnant women with gingivitis (3.7%) and in a higher percentage of pregnant women with periodontitis (33.3%). Conclusion: Socransky Red Complex was found only in cases of periodontal diseases and is not related to blood pressure and/or high levels of blood glucose. Keywords: periodontal disease, pregnancy, Socransky Red Complex