The intersection of race and socioeconomic status is associated with inflammation patterns during pregnancy and adverse pregnancy outcomes

Background: Preterm birth rates are higher among individuals of lower socioeconomic status and non-White race, which is possibly related to life-course stressors. It is important to understand the underlying mechanisms of these health disparities, and inflammation is a possible pathway to explain the disparities in birth outcomes. Objective: In this study, we aimed to determine whether patterns of inflammation differed by maternal race and socioeconomic status. Study design: Seven hundred and forty-four participants in a multi-site, prospective study of pregnancy and birth outcomes provided biological and psychological data between 12′0-20′6 weeks gestation. Participants with recent infection, fever, antibiotics or steroid treatment were excluded. Cytokines including INFɣ, IL-10, IL-13, IL-6, IL-8, and TNFα, and the acute phase protein CRP were measured in serum and values and were log-transformed for normality when appropriate, and a non-orthogonal rotation (Oblimid) was performed to allow the extracted factor to inter-correlate. IFNγ, IL-8, IL-10, IL-6, TNF-a, and IL-13 loaded onto Inflammatory Factor 1 (IF-1), while CRP and IL-6 loaded onto Inflammatory Factor 2 (IF-2). Race and education were collected via self-report during an in-person study visit. Multivariable models were used to determine the association of race and SES with IF-1 and IF-2 during the second trimester, and a mediation model was used to examine if inflammation is on the causal pathway. Models were adjusted for study site, prenatal age, pre-pregnancy BMI, smoking during pregnancy, and gestational age at the time of blood collection. Results: Six hundred and five participants were included in our final analysis, with 61.2% of low or moderate SES, and 35.5% identifying as a person of color (POC). Identifying as a POC, being of low and moderate SES, and being both low-SES and POC or moderate-SES and POC were associated with higher odds of preterm birth and lower birth weight percentile infants. Low SES POC participants had significantly higher IF-1 and IF-2 scores when compared to high-SES White participants. Additionally, higher IF-1 and IF-2 were associated with shorter gestation. In the mediation analysis, we observed a significant direct effect of race/SES on preterm birth; however, the results did not support an indirect pathway where IF-1 or IF-2 acted as mediators. Conclusion: Maternal race and SES are significantly associated with inflammatory biomarkers during pregnancy, and when race and SES are considered in combination, they are stronger predictors of adverse pregnancy outcomes than when evaluated separately.