Effect of a Nonoptimal Cervicovaginal Microbiota and Psychosocial Stress on Recurrent Spontaneous Preterm Birth
Authors: Gerson Kristin D. , Mccarthy Clare , Ravel Jacques , Elovitz Michal A. , Burris Heather H. 
Published: October 2020

Objective While select cervicovaginal microbiota and psychosocial factors have been associated with spontaneous preterm birth, their effect on the risk of recurrence remains unclear. It is also unknown whether psychosocial factors amplify underlying biologic risk. This study sought to determine the effect of nonoptimal cervicovaginal microbiota and perceived stress on the risk of recurrent spontaneous preterm birth.
Study Design This was a secondary analysis of a prospective pregnancy cohort, Motherhood and Microbiome. The Cohen's Perceived Stress Scale (PSS-14) was administered and cervical swabs were obtained between 16 and 20 weeks of gestation. PSS-14 scores ≥30 reflected high perceived stress. We analyzed cervicovaginal microbiota using 16S rRNA sequencing and classified microbial communities into community state types (CSTs). CST IV is a nonoptimal cervicovaginal microbial community characterized by anaerobes and a lack of Lactobacillus. The final cohort included a predominantly non-Hispanic Black population of women with prior spontaneous preterm birth who had recurrent spontaneous preterm birth or term birth and had stress measurements (n = 181). A subanalysis was performed in the subset of these women with cervicovaginal microbiota data (n = 74). Multivariable logistic regression modeled adjusted associations between CST IV and recurrent spontaneous preterm birth, high stress and recurrent spontaneous preterm birth, as well as high stress and CST IV.
Results Among the 181 women with prior spontaneous preterm birth, 45 (24.9%) had high perceived stress. We did not detect a significant association between high stress and recurrent spontaneous preterm birth (adjusted odds ratio [aOR] 1.67, 95% confidence interval [CI]: 0.73–3.85). Among the 74 women with prior spontaneous preterm birth and cervicovaginal microbiota analyzed, 29 (39.2%) had CST IV; this proportion differed significantly among women with recurrent spontaneous preterm birth (51.4%) compared with women with term birth (28.2%) (p = 0.04). In models adjusted for race and marital status, the association between CST IV and recurrent spontaneous preterm birth persisted (aOR 3.58, 95% CI: 1.25–10.24). There was no significant interaction between stress and CST IV on the odds of spontaneous preterm birth (p = 0.328). When both stress and CST IV were introduced into the model, their associations with recurrent spontaneous preterm birth were slightly stronger than when they were in the model alone. The aOR for stress with recurrent spontaneous preterm birth was 2.02 (95% CI: 0.61–6.71) and for CST IV the aOR was 3.83 (95% CI: 1.30–11.33). Compared to women with neither of the two exposures, women with both high stress and CST IV had the highest odds of recurrent spontaneous preterm birth (aOR = 6.01, 95% CI: 1.002–36.03).
Conclusion Among a predominantly non-Hispanic Black cohort of women with a prior spontaneous preterm birth, a nonoptimal cervicovaginal microbiota is associated with increased odds of recurrent spontaneous preterm birth. Adjustment for perceived stress may amplify associations between CST IV and recurrent spontaneous preterm birth. Identification of modifiable social or behavioral factors may unveil novel nonpharmacologic interventions to decrease recurrent spontaneous preterm birth among women with underlying biologic risk.
Key Points