Determination of the Microbial Shift in the Gingival Sulcus of Women during Each Trimester of Pregnancy: A Cross-Sectional Study

<i>Background and Objectives</i>: This study aims to identify types of bacterial species in women visiting obstetrics/gynecology centers in Riyadh City, Saudi Arabia, during different pregnancy trimesters. <i>Materials and Methods</i>: This cross-sectional study was conducted among pregnant and nonpregnant women seeking care at Alyamamah Hospital, obstetrics/gynecology center, Riyadh, Saudi Arabia. A total of 110 [pregnant = 90 and nonpregnant = 20] individuals were recruited based on inclusion/exclusion criteria. Personal data, plaque index (PI), and gingival index (GI) were recorded. Bacterial samples were collected using sterile absorbent paper points from the gingival sulcus of pregnant females during the first, second, and third trimesters and compared to a control group of nonpregnant females. Thioglycolate broth containing the absorbent paper points was incubated at 37 °C for 24-48 h. After growth, the microorganisms were subjected to a Gram stain. The VITEK 2 system and conventional methods were used to identify various types of bacterial species from the gingival sulcus of pregnant and nonpregnant women. Chi-square tests and nonparametric tests were applied to the data. <i>Results</i>: The bacterial characterization indicated that <i>Actinomyces naeslundii</i> (AN) was the most predominant bacteria found in the study participants, followed by <i>Lactobacillus fermentum</i> (LF) (23.6%), <i>Veillonella</i> (VL) (10%), and unidentified organisms (9.1%). When the presence of subgingival bacterial species was compared between pregnant and nonpregnant women, a statistically significant difference was observed (<i>p</i> < 0.001). LF was the predominant bacteria in 9 nonpregnant women (45%) and 8 pregnant women in the first pregnancy trimester (44.4%). However, during the second (17 women: 48.6%) and third pregnancy (17 women: 45.9%) trimesters, AN becomes the predominant bacteria. A statistically significant difference was observed when the prevalence of various bacterial species was compared across the three pregnancy trimesters (<i>p</i> = 0.010). The plaque and gingival scores of pregnant and nonpregnant women showed no significant difference. <i>Conclusions</i>: In different trimesters of pregnancy, pregnant women's gingival crevices showed significant microbial changes without affecting gingival inflammation.