Pro-inflammatory diet in pregnancy associated with increased risk of abnormal perinatal outcomes: evidence from dietary inflammatory index in the UK biobank.

OBJECTIVES

This study aimed to investigate the association between a pro-inflammatory diet in pregnancy, assessed via the Dietary Inflammatory Index (DII), and abnormal perinatal outcomes (APOs), including miscarriage and stillbirth. Leveraging the UK Biobank cohort, we evaluated whether higher DII scores were associated with increased APOs risk. Additionally, we explored interactions between DII, lifestyle factors (physical inactivity, smoking exposure), and socioeconomic determinants to identify modifiable pathways for reducing APOs.

METHODS

We analyzed 10,353 women from the UK Biobank with pregnancy records and ≥2 valid 24-h dietary assessments (collected during pregnancy between 2006 and 2019). DII scores were computed using intakes of 20 nutrients (e.g., fats, vitamins, and fiber) linked to inflammation. APOs (miscarriage/stillbirth) were derived from self-reported questionnaires. Covariates (age, BMI, physical activity, income, education, and smoking) were adjusted in logistic regression models comparing DII quartiles (Q1: anti-inflammatory; Q4: pro-inflammatory). A sensitivity analysis using miscarriage and stillbirth as separate outcomes was conducted. A formal test for nonlinear trend (p-for-trend) was performed across quartiles. Analyses used R 4.1.1 and Python 3.7.

RESULTS

Compared with the most pro-inflammatory group (Q4), the risk of abnormal perinatal outcomes was 14% lower in the most anti-inflammatory group (Q1; OR = 0.86, 95% CI: 0.76-0.97) in model 1, 13% lower (OR = 0.87, 95% CI: 0.77-0.98) in model 2, and 14% lower (OR = 0.86, 95% CI: 0.76-0.97) in model 3. Additionally, compared with the most pro-inflammatory group (Q4), the low anti-inflammatory group (Q2) was associated with an 17% lower risk of abnormal perinatal outcomes in model 3 and low pro-inflammatory group (Q3) was associated with an 12% lower risk of abnormal perinatal outcomes in model 3. Physically inactive women, smokers, and those with lower education had higher DII scores and APO incidence (p < 0.001). Household income and tobacco exposure were also significantly associated with APOs (p < 0.05).

CONCLUSIONS

Higher DII scores were associated with higher risks of miscarriage and stillbirth. Anti-inflammatory diets confer protective effects, underscoring diet optimization as a key intervention strategy. Lifestyle factors (inactivity, smoking) and lower education amplify both pro-inflammatory diets and APO susceptibility. These findings support integrating dietary inflammation screening into prenatal care to mitigate adverse outcomes.