The association between Porphyromonas gingivalis-specific maternal serum IgG and low birth weight

Background: In Alabama, low birth weight (LBW) infants are about 20 times more likely to die before their first birthday compared to normal birth weight infants. While the rate of LBW has been consistently higher among African Americans compared to whites, there has been a gradual increase in LBW for both African Americans and whites over the last 15 years. In an attempt to identify modifiable risk factors for LBW, we have previously reported that a pregnant woman's poor periodontal health may be an independent risk factor for low birth weight. Methods: A predominantly African American and socioeconomically homogeneous group of 448 women was followed from the second trimester of their first pregnancy. Thirty-nine LBW cases were observed at the end of follow-up. Using 17 preterm LBW cases and 63 randomly selected controls from the above cohort, the periodontal pathogen-specific maternal serum IgG levels during the second trimester of pregnancy were evaluated in relation to birth weight of the infant, while controlling for known risk factors for LBW. Results: Porphyromonas gingivalis (P.g.)-specific maternal serum IgG levels were higher in the LBW group (mean 58.05, SE = 20.00 μg/ml) compared to the normal birth weight (NBW) group (mean 13.45, SE = 3.92 μg/ml; P= 0.004). Women with higher levels of P.g.-specific IgG had higher odds of giving birth to LBW infants (odds ratio [OR] = 4.1; 95% confidence interval [CI] for odds ratio = 1.3 to 12.8). This association remained significant after controlling for smoking, age, IgG levels against other selected periodontal pathogens, and race. Conclusions: Low birth weight deliveries were associated with a higher maternal serum antibody level against P. gingivalis at mid-trimester.