Gingival changes during pregnancy: II. Influence of hormonal variations on the subgingival biofilm

Aim: To determine whether the exacerbated gingival inflammation that develops in pregnant women is related to a change in the subgingival biofilm induced by the increase in hormone levels during pregnancy. Material and Methods: This open cohort study included 48 pregnant and 28 non-pregnant women without periodontitis. Pregnant women were evaluated in the first, second and third trimester and at 3 months after delivery. Non-pregnant women were evaluated twice, with a 6-month interval, assessing microbiological, clinical and hormonal variables at each visit. Total anaerobic counts and frequency of detection and proportions were calculated. The Friedman test with the Bonferroni correction was used for intra-group comparisons and Mann-Whitney U-tests for inter-group assessment. Correlations were analysed by means of Spearman's rank correlation coefficient. Results: Proportions of the subgingival periodontal pathogens did not differ throughout pregnancy, although significant differences were found for all the pathogens after delivery. Porphyromonas gingivalis-positive patients presented an increase in gingival inflammation (p < 0.001) that was not related to plaque. Correlations were found between maternal hormone levels and P. gingivalis and Prevotella intermedia. Conclusion: Qualitative differences in periodontal pathogens were found from pregnancy to post-partum. Patients harbouring P. gingivalis presented and increased gingival inflammatory status.