Maternal Stress Potentiates the Effect of an Inflammatory Diet in Pregnancy on Maternal Concentrations of Tumor Necrosis Factor Alpha

Abstract

Maternal inflammation during pregnancy is known to adversely impact fetal development, birth outcomes, and offspring physical and mental health. Diet and stress have been identified as important determinants of inflammation, yet their combined effects have not been examined in the context of pregnancy. The aim of this study was to examine the relationship between maternal diet with inflammatory potential and psychological stress, and to determine their interaction effect on concentrations of tumor necrosis factor (TNF)-α across pregnancy. We conducted a prospective longitudinal study of n = 202 women with three assessments during pregnancy, which included: ecological momentary assessment (EMA) of maternal stress using the perceived stress scale (PSS) short version; 24-h dietary recalls from which the dietary inflammatory index (DII) was computed; and serum measurements of TNF-α. Across pregnancy, higher perceived stress was associated with consumption of a more pro-inflammatory diet (r = 0.137; p < 0.05). In a linear regression model adjusted for covariates, DII was positively associated with TNF-α (B = 0.093, p = 0.010). The effect of the pro-inflammatory diet on concentrations of TNF-α was more pronounced in women reporting higher levels of stress (B = 0.134, p = 0.018 for DII*PSS interaction). These results highlight the need to consider nutrition and stress concurrently in the context of inflammation during pregnancy.

Keywords: dietary inflammatory index; inflammation; pregnancy; prenatal diet; prenatal stress; tumor necrosis factor-alpha.

Figure 1

Hypothesized interaction between maternal prenatal diet and stress and the influence on systemic inflammatory profile in pregnancy.

Figure 2

Structure of prenatal assessments in early (10–12 weeks), middle (20–22 weeks), and late (30–32 weeks) pregnancy.

Figure 3

Bar chart depicting the association of prenatal DII score with maternal PSS. CI: Confidence Interval. Caption: DII, dietary inflammatory index; PSS, perceived stress score. High and low PSS is operationalized as mean pregnancy PSS score above and below the median value. The DII score of the maternal diet is higher among women with a higher PSS score, indicating consumption of a more pro-inflammatory diet among women experiencing higher stress levels. PSS and DII as continuous variables were correlated in statistical analyses.

Figure 4

Mean pregnancy TNF-α levels among pregnant women with high and low perceived stress scores, according to DII tertile. CI: Confidence Interval. Caption: DII, dietary inflammatory index; PSS, perceived stress score; TNF, tumor necrosis factor. Although DII, PSS, and TNF-α were entered to regression models as continuous variables, for the purpose of graphically depicting the effect of the DII*PSS interaction term on TNF-α, mean pregnancy DII was divided into tertiles and mean pregnancy PSS was dichotomized by the median value. A pro-inflammatory diet influences higher TNF-α levels only among women reporting higher perceived stress scores across pregnancy. Women who report lower perceived stress levels do not experience any difference in TNF-α levels, regardless of the inflammatory potential of their diet.