Background <p>Maternal periodontal disease is a prevalent condition that has been widely investigated for its association with adverse pregnancy outcomes, including preterm birth and low birth weight. The present study aimed to evaluate and compare the clinical and microbiological oral conditions of high-risk and low-risk pregnant women and to correlate these findings with the presence of periodontopathogenic microorganisms in the oral cavity and umbilical cord blood of their newborns.</p> Methods <p>A total of 54 pregnant women and their respective newborns were evaluated during the perinatal period and allocated into two groups: a high-risk pregnancy group and a control group. High-risk pregnancy was defined according to criteria established by the Brazilian Ministry of Health, including systemic and obstetric risk conditions. Maternal clinical assessment included the following periodontal parameters: visible plaque index (VPI), gingival bleeding index (GBI), probing depth (PD), and clinical attachment level (CAL). Microbiological samples were collected from oral soft tissues (tongue and cheek swabs) and subgingivally (using size 30 sterile paper points). Umbilical cord blood was collected immediately after clamping, and oral microbiological samples from the newborns were obtained using swabs. The presence of <i>Aggregatibacter actinomycetemcomitans</i> (Aa), <i>Porphyromonas gingivalis</i> (Pg), and <i>Tannerella forsythia</i> (Tf) was investigated using real-time PCR. Statistical analysis was performed using Kruskal-Wallis, Mann-Whitney, and Spearman’s correlation tests to explore associations between clinical and microbiological data. The chi-square test was used for categorical data.</p> Results <p>Evidence of periodontal disease was observed in both groups, with a statistically significant increase in the detection of Aa in the maternal oral samples from women in the high-risk group (<i>p</i> = 0.042). A positive correlation was also found between CAL and the presence of Tf in subgingival samples, indicating that higher CAL values were associated with greater bacterial load (<i>p</i> &lt; 0.05). However, no statistically significant associations were identified between maternal periodontal status and adverse obstetric outcomes (<i>p</i> &gt; 0.05).</p> Conclusions <p>The detection of periodontopathogenic microorganisms in umbilical cord blood and neonatal oral samples suggests the possibility of maternal-fetal microbial transmission, although no association was observed with adverse obstetric outcomes.</p> Clinical trial number <p>not applicable.</p>