The relationship between salivary bacterial flora and adverse pregnancy outcomes

Many studies have shown that periodontal pathogens are emerging as a risk factor for preterm delivery and low birth weight, but there are few studies about the relationship between other oral bacteria and pregnancy outcomes. The aim of the present study was to determine the relationship between salivary bacteria and pregnancy outcomes.

This cohort study was performed on 300 pregnant women who were recruited from the prenatal clinic of Zeynab Hospital in Tehran during 2009-2010. The patients’ demographic and pregnancy data were recorded. Using samplers, saliva samples were collected about one hour after breakfast. Microbial evaluation was performed by counting the bacteria based on their shape and the Gram reaction. The studied bacteria were composed of gram-positive and negative cocci, gram-positive and negative bacilli, spirilla, spirochetes, yeasts, fusiform bacteria and actinomycetes.

The data on the bacteriological profile and pregnancy outcome of 243 out of the 300 eligible participants of the study were completed. Five cases (2%) had intra uterine fetal death (IUFD) while 238 (98%) delivered live infants. There was a significant statistical relationship between the mean of gram-negative cocci and IUFD (P=0.04). 10 cases (4.1%) of 243, experienced adverse delivery outcomes and 233 cases (95%) had normal delivery. The adverse pregnancy outcomes had a significant relationship with the presence of spirochetes in saliva (P<0.05) but this relationship was not true for the other bacteria.

Some oral bacteria may pose a risk for premature deliveries and low birth weights.