Effect of <i>Porphyromonas gingivalis</i> infection in the placenta and umbilical cord in pregnant mice with low birth weight

<b>Objective:</b> Growing evidence indicates an association between periodontitis and delivery outcome; however, the mechanism is unclear. This study aimed to investigate the influence of <i>Porphyromonas gingivalis</i> (<i>Pg</i>) infection on delivery outcome in mice. <b>Materials and methods:</b> Bacteremia was induced in pregnant Slc:ICR mice (8 weeks old) by intravenous injection of <i>Pg.</i> Mice were randomly divided into a control group (CO), and those receiving <i>Pg</i> injection at gestational day 1 (GD1), gestational day 15 (GD15) or every day (ED). Delivery outcome, <i>Pg</i> infection, and gene expression in the placenta and umbilical cord were evaluated. <b>Results:</b> Birth weight was lower in the ED and GD15 groups than in the CO group. A remarkable increase in anti-<i>Pg</i> IgG antibody was observed in the ED and GD1 groups, although <i>Pg</i> was not detected in the placenta or umbilical cord. mRNA expression of <i>Tnfα</i> and <i>Il6</i> in the placenta, and <i>Hif1α</i> in the umbilical cord, was significantly increased in the ED group. Microarray analysis of the umbilical cord revealed increased expression of several genes including <i>Orm1</i>, <i>Mgl2</i>, <i>Rps6ka3</i> and <i>Trim15</i> in the ED group. <b>Conclusions:</b><i>Pg</i> infection during the third trimester caused low birth weight and inflammation in the placenta and umbilical cord.