Nitric Oxide, Oxidative Stress and Streptococcus mutans and Lactobacillus Bacterial Loads in Saliva during the Different Stages of Pregnancy: A Longitudinal Study

Hormonal changes associated with pregnancy promote oral bacterial growth, which may affect salivary nitric oxide (NO) levels, oxidative stress (OS), and antioxidant capacity (AC). We hypothesized that caries-related bacterial load, NO level, and OS in the saliva change with advancing gestation. The aim of this study was to investigate longitudinal changes in salivary NO, OS, and AC during pregnancy and correlate them with Streptococcus mutans ( SM ) and Lactobacillus ( LB ) colonization at different stages of pregnancy. We assessed NO level by Griess method, OS by measuring malondialdehyde (MDA), AC by ABTS radicals and bacterial load by culturing SM and LB in the saliva of pregnant women ( n = 96) and compared with non-pregnant women ( n = 50) as well as between different stages of pregnancy. Compared with non-pregnant women, NO was 77% higher (4.73 ± 2.87 vs. 2.67 ± 1.55 µM; p < 0.001), MDA was 13% higher (0.96 ± 0.27 vs. 0.85 ± 0.22 nM; p = 0.0055), and AC was 34% lower (60.35 ± 14.33 vs. 80.82 ± 11.60%; p < 0.001) in the late third trimester. NO increased with advancing gestation, but AC and OS did not change significantly during pregnancy. SM were more abundant in pregnant women compared with non-pregnant ( p = 0.0012). Pregnancy appears to have an adverse impact on oral health emphasizing the importance optimal oral healthcare during pregnancy.