Vitamin D Status as a Late Pregnancy Biomarker of Perceived Stress

Background/Objectives: Stress during pregnancy critically impacts maternal and fetal health. While prior research has linked sociodemographic and biological factors to stress levels, the role of specific biomarkers, such as vitamin D (VD), remains unexplored. This study examined the relationships among sociodemographic factors, VD status (as measured by serum 25-hydroxyvitamin D [25(OH)D] concentration), and perceived stress in pregnant women. We hypothesized that 25(OH)D concentration would be associated with perceived stress levels during pregnancy. Methods: A post hoc analysis of the Kellogg Pregnancy VD study was conducted on a cohort of 232 pregnant women with Perceived Stress Scale (PSS-10) scores at months 2, 5, and 7 with corresponding 25(OH)D concentrations. PSS-10 scores were classified into two groups: patients with scores of 0–13 were considered to have low stress, while those with scores of 14–40 were considered to have moderate-to-high stress. Logistic regression models identified factors associated with moderate-to-high stress. Results: At month 2, univariate analyses showed that being married (p = 0.002), having a college education (p = 0.0013), and lower BMI (p = 0.018) were associated with lower perceived stress, whereas Black race was associated with higher perceived stress (p = 0.027). By month 7, higher serum 25(OH)D concentration was the only significant predictor of perceived stress in univariate analysis (p = 0.002). In multivariate models at month 7, 25(OH)D approached significance (p = 0.053). Conclusions: Early in pregnancy, race, marital status, college education, and BMI were significantly associated with PSS-10 score. By month 7, 25(OH)D concentration over time emerged as a factor that was significantly associated in univariate analysis and showed a trend toward significance in multivariate models. VD status, as measured by 25(OH)D concentration, may act as a biomarker of stress during pregnancy. Results warrant further study in prospective intervention trials.