A collaboration led by a periodontal researcher from the University of Pennsylvania School of Dental Medicine found the link.
While a number of factors are associated with an increased rate of preterm birth, such as low body-mass index, alcohol consumption and smoking, the study adds to the body of research that suggests oral infection may also be associated with such an increase.
The study looked at 322 pregnant women, all with gum disease. Half the group was given oral-hygiene instruction and treated with scaling and root planning, which consists of cleaning above and below the gum line. The second half received only oral-hygiene instruction.
The incidence of preterm birth was high in both the treatment group and the untreated group: 52.4 percent of the women in the untreated control group had a preterm baby compared with 45.6 percent in the treatment group. These differences were not statistically significant.
However, researchers then looked at whether the success of periodontal treatment was associated with the rate of preterm birth. Participants were examined 20 weeks after the initial treatment, and success was characterized by reduced inflammation, no increase in probing depth and loosening of the teeth.
Within the treatment group of 160 women, 49 were classified as having successful gum treatment and only four, or 8 percent, had a preterm baby. In comparison, 111 women had unsuccessful treatment and 69, or 62 percent, had preterm babies.
The results show that pregnant women who were resistant to the effects of scaling and root planning were significantly more likely to deliver preterm babies than those for whom it was successful.
The study has been published in the journal BJOG: An International Journal of Obstetrics and Gynaecology. (ANI)