Graduation Year

2022

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Nursing

Major Professor

Maureen Groer, Ph.D., RN, FAAN

Committee Member

Stephanie Prescott, Ph.D., APRN, NNP-BC

Committee Member

Allyson Duffy, Ph.D., RN

Committee Member

Amy Alman, Ph.D.

Keywords

Salivary Microbiome, Adverse Pregnancy Outcomes, Cortisol, Stress, Depression

Abstract

The purpose of this dissertation was to longitudinally examine the salivary microbiome during the second and third trimesters of pregnancy and explore its associations amongst adverse pregnancy outcomes (preterm birth, gestational diabetes mellitus, and hypertensive disorders of pregnancy), perceived stress and depression, and hair/salivary cortisol levels. The specific aims were to (1) explore the literature for studies longitudinally examining the oral microbiome during pregnancy using a scoping review guided by the Arskey and O’Malley framework; (2) to examine the salivary microbiome for changes in diversity and abundance during the second and third trimesters during pregnancy and its association with adverse pregnancy outcomes (preterm birth, gestational diabetes mellitus, and hypertensive disorders of pregnancy); and (3) to explore associations with the salivary microbiome and measures of perceived stress and depression and hair/salivary cortisol levels.

In the first aim, the scoping review identified six studies that had longitudinally examined the oral microbiome throughout pregnancy. These studies identified alterations in alpha diversity throughout pregnancy (n = 3), pathogenic bacteria during pregnancy (n = 3), and differences in the composition of the microbiome based on socioeconomic status and antibiotic use (n = 1). However, some studies reported stability in the oral microbiome throughout pregnancy (n = 3). Only two studies examined adverse pregnancy outcomes and their associations with the oral microbiome, and one reported difference in the community gene composition. In the second aim, we found that the salivary microbiome demonstrated stability throughout pregnancy by alpha and beta diversity measures. We found that individuals who were diagnosed with preeclampsia had differences in beta diversity, indicating compositional differences to the salivary microbiome at the genus level (F = 2.65, df = 1, p = 0.015). We also found differences in beta diversity at the species level in those who were Hispanic compared to those who were not Hispanic (F = 1.7183, df = 1, p = 0.04). In the third aim, we found that there were alterations in the relative abundances of bacteria associated with perceived stress and hair/salivary cortisol levels. Specifically, individuals with low levels of perceived stress had an increase in Neisseria meningitidis bacteria (β = 1.169, p = 0.012) and salivary cortisol levels were associated with bacteria belonging to the Solobacterium genus (β = - 0.006, p < 0.02). Hair cortisol levels during the second and third trimesters were associated with Phocaeicola abscessus (β = 0.007, p < 0.001; β = 0.008, p < 0.001), Treponema medium (β = 0.007, p = 0.012; β = 0.007, p = 0.014), Prevotella dentalis (β = 0.007, p = 0.019; β = 0.007, p < 0.001), and unidentified bacteria belonging to the Phocaeicola genus (β = 0.007, p = 0.012; β = 0.005, p < 0.001) and Pseudoramibacter genus (β = 0.007, p = 0.012; β = 0.007, p < 0.001), respectively. This dissertation demonstrated that the salivary microbiome while stable throughout the second and third trimesters, is altered by perceived stress, hair/salivary cortisol levels, has compositional differences in individuals who were Hispanic, and/or were diagnosed with preeclampsia.

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